I agree but it should be noted
Bishop did not disobey an order to abort. His spotter called "No Joy" and tried to end the mission. Muir was at camp and having difficulty picking up the transmission. The General was still in Bishops sights. He knew that if the Helo cleared his line of sight, he could complete the mission which was to terminate the General. Getting out alive was up to him.

Why didn't they just save time and ask him right away if he wanted to join the CIA or not.
I think Muir wanted to keep an eye on him to better gauge his qualities. I think the films leads us to believe that Muir thought Bishop showed promise based on what he saw in Vietnam, but was not convinced of his suitability. E.G. He didn't abort the mission in Vietnam when ordered too, but carried it through.

It's a cool scene to show how cold and calculating the game is. But one thing that bothered me is that someone who gets bored at a foreign posting because he can't be bothered to learn a new language, is that good material for an agent? It's not like it's Uzbekistan.

Post Vietnam the CIA, especially those background spooks in Vietnam were not well liked by the armed services. Recruiting for all sides of the civil service, especially intelligence was difficult. Back in Vietnam, the agents had a reputation of being these Harvard, silver spoon in their mouth, type of guys. They were called Christians in Action.
Putting Pitts character in Germany was an extremely boring posting. After a couple of months, he'd be willing to do practically anything. It reflects the type of mind game and power the CIA had back in those days.