I think that sunderer drivers should have the ability to choose which type of classes spawn. If there is a vehicle rush coming, then the driver would choose HA and engie. If your ghosting a base then choose only infil and la.
Griefing could go off the chart with this one. Just imagine, you are a griefer who usually just kills his own team. This could be because he wants 'his' faction to win and he's helping his teammates or because he just wants to be an ***. But instead of killing his team, he'll destroy the Sunderer, replace it with his own and set it to the most useless class for the situation. 100% infiltrators for instance while you need to breach a base. 100% LA when you are indoor fighting etc. A big no to controlling what class people spawn as. I am a dedicated LA player and I don't want to be forced into a class I don't want. I rarely ever touch my Heavy because I don't like playing as one, so why should I accept it just because someone else choose it?
I don't know how you felt this might be a good idea at all. I can see "recommended classes to spawn as" but not "forced classes to spawn as."