My guess is he filmed several movies before his death. Looking at some of the movies after his death they look like straight to video small budget films. Which could possibly mean the release of the movies were delayed or they couldn't get a distributor. Or they got a distributor years down the line after filming.

no no no. OBVIOUSLY all movies come out the DAY they were filmed. It makes no sense at all to think he could have been seen in anything at all after he died. this is real life man, come on.

The easy answer is that his parts were already filmed and the movies, for one reason or another, were delayed. That happens pretty often in low-budget films that fail to find a distributor right away.
In space, no one can hear you scream. On IMDB, we can hear you, but we just don't give a crap.

This man was so good in what he did, that he received a 'get-out-of-heaven free card' and came down to finish his last projects. Problem solved.