This extended my RJ play time to a degree that makes me not want to play it ever again.

[(PSN)rexis12]

And this was with the missile battery mission, which means I couldn't even just zip in and out.

Seriously,

[(XBOX)Shodian]

In the time you waited for your crewmate to shoot it you could have been in and out. 

I find that if they are being attacked or if there's something else they can shoot they'll be distracted by that instead of the objective. Also try swapping pilots, that sometimes works for me when their ai bugs out.

[RobWasHere]

Don't even bother with AI trying to shoot the radiators. Don't assign the pilot, park the RJ in front of objective door, port back in, use Shatter Burst, fly inside. Pulse turbine is even faster if you just exit the building on foot instead of porting back.