White guilt.
Ordell R-O-BB-I-E was playing up the white guilt anglebut jokingly. While he didn't know, nor care, what the truth was, he was teasing Max about white guilt, joking that the only reason Max the white boss took a picture with "that big mandingo-lookin' niqqa" Winston, was because he wanted the world to know he
wasn't
a white slave master. I.E. White guilt.
Ordell is being a racist dick.

Pidder Padder? Make my Heart go Boom Bap and Then We'll Talk!

Why are you taking this so far? Winston is a big guy, Max has the picture hanging there to show he has muscle behind him and maybe even more importantly to have a nice picture of his good employee in his office.
Until I saw this post the "white/black slave" never occurred to me, every black with a white boss must be a slave?
That was real? I saw that movie, I thought it was bullsh*t

I think there are two motives why he refered to the photo. One is Ordell wants to know how Max Cherry ticks and what he's able to do in order to dominate him. The other one is his underlying belief that all whites are supremacists who see all blacks as subordinate to them. He would hardly believe, that Max and Winston could be friends who enjoy a fishing trip together. Later in the movie, when Ordell and Max drive from Ordell's hideout to Max's office, Ordell is surprised to hear the Delfonics tape and Max says "they're pretty good," which confuses Ordell because a white man enjoying black music doesn't fit into his world view.

Ordell was being a smart-ass generally during the scene. I would have to see it again but does he even have his feet up on a desk at one point? Ordell's sassy self-confidence declines as the movie continues, however.
"Chicken soup - with a beep straw."

Also, you can tell that Winston trusts Max and that they are close, because at the end of the movie Winston accepts a dangerous job (to find Ordell) and tells Max that he doesn't need to know the details, the implication being that he doesn't need to know because he trusts Max's judgement.
"No man yet found drinks his tea blacker"

Ordell's just an Alpha male trying to get under Max's skin, and I love the way Max directly rebuffs Ordell at every turn from his comments about Winston in the photo to later on when Ordell tries to discount his bail bond costs after he kills Beaumont and tries to use the same money to bail Jackie. Without even saying anything you can see Max is onto Ordell and who he IS. As Max said, white guilt doesn't work on him.

Ordell definitely wanted to mess with Max, benignly or not.
Ordell saw the picture, and asked. Winston's this huge black man, and he works for Max Cherry. Ordell asks if it was Max's idea to take that picture, which it could have been.
Max is a bail bondsman. He deals with a fair number of dangerous people (including Ordell himself!) and would need to have some kind of protection. Also, as stated, Winston "finds people who don't want to be found".
I don't reject the idea that Max and Winston are close, personally. It's just their closeness doesn't make it any less obvious Max needs someone like Winston around. Ultimately Winston plays a part in Ordell's downfall. Ordell was right to be "concerned".
Never hate your enemies. It affects your judgment.
-Michael Corleone

Thank you Harold. I think way too much is being read into what is more or less Ordell's attempt to get under Max's skin with a snide comment. I agree with your assessment.

The scene is mostly just to set up that Winston is his employee, so that when he shows up later in the movie, we know who he is and what he does.

The only thing I can guess is that Max did not want Winston to feel like he was using him as a white slave master and had a photo taken together to show how close they were and then displayed it prominently in the office. Somehow Ordell sees through this charade and confronts Max about it who uncomfortably changes the subject.
This is the conclusion that Ordell comes to, yes. And, you Alex, are coming to the same conclusionthis is what the writing wants us to see as well.
Max is annoyed by Ordell because Ordell is messing with him. "hey..you didn't wash your hands" as Max comes out of the bathroom So again, Max ignores Ordell with his comment about it was his (max's) idea to take the picturewhen it's just as likely it was an innocent photo of two co workers doing what they do.
Despite "popular" opinionmost white people are not racist. Certainly, Max doesn't show any signs of such. Max hired an enforcer type and Winston fit the bill. Bonus was that he (winston) had a knack for finding people that didn't want to be found. So, big AND smart. Why not take a photo with a very good employee?
How about it's more likely that Max or even Winston wanted the photo taken for a keepsake of a particular moment in their career?
Heckwe really don't know the history between Max and Winston at all. (I tried to read Rum Punch, but couldn't get through it.QT departed a fair amount from the book) So it could be that M and W were equal partnersor at least more that just boss/employee.

"A white slave master"? Winston was hired muscle. I don't think there was any doubt between Max and Winston as to what their relationship was based on. Winston provided a service and was compensated for it. Ordell read that in the picture. Max only reacted to the obvious implication of the pictureSCREW ME OVER AND THIS BIG BLACK MAN WILL HUNT YOU DOWN.