Obvious spoilers. Upon my first introduction to Father and having determined him to be a complete [censored] nozzle, I decided to unload a relentless and extremely devastating barrage of plasma into his smug bearded face. At which point I came under fire from everyone in the vicinity. I valiantly fought my way to the narrow corridor leading to the exit. So far so good. Except, when the lift doors pinged open I was met with a spawn of at least fifty synths, all armed to the teeth. Given that it was quite a confined area, getting through them was impossible (at least for me), so I had to load a previous save, spare father and resist my homicidal tendencies.

Is this supposed to happen? Perhaps it’s a mechanic to dissuade you from killing father and exiting the institute prematurely? It certainly worked for me.

It's supposed to happen, and probably the only realistic response to a major act commitied by the SS anywhere in the game. It's not the only massive spawn you'd have to fight either.

A faction infamous for its teleportation technology will teleport, literally, an army on top of you if you kill its faction leader.

I see nothing wrong with this.

As much of a shooter as FO4 is, "Shoot first, ask questions later" is still a bad idea.