I think that is a good idea to keep in mind while balancing him in game as well. Instead if him having to be up in the front line like the popular dps these days it would be interesting to see his position be at more of a mid range.
I also thought of giving him a ‘pulse’ ability in sentry as a form of CC in the areas immediately close to him. Like letting out some excess energy almost like the plasma rifle from Doom 2016.
You could make it so Bastion had to walk for so long in Recon to “Charge” it. I don’t know about any numbers for it but I think that would make him less diveable with out changing his effectiveness against Road Hog, Hanzo, or Widow.
Idk Food for thought. Maybe someone can come up with a better idea from this 
Idk if it is even a good idea I just want to bring more ideas to the table