When aliens rush, if a single human shoots the alien and it dies, he will get he will get all the credits. I don't see what's wrong with giving a few of them to the builder since he can't shoot them and anyway his team will get the cred (oh come on, when aliens rush there are humans in base).
Also - sometimes, as a builder, I need jetpack (moving base, foward base... or just regular building) but I don't have enough cred and I hve to ask them for money - because they got it too fast or whatever. I don't see what's wrong if it gets fixed.