Uhm you understand that by the time you have 2 mgs and 2 grens, they have 4 riflemen squads, they just need to let one squad be pinned, or two, and let the other ones come in from flanks. Your supporting infantry can't be everywhere. I understand you are trying to defend the USF, but such claims are out of order..
I really don't see the problem described there, there's a whole other HMG and Gren that can protect the flanks if one of both of those are occupying two rifles (which they should be able to). So I'll be saying again I find the real problem is teching costs making it very unlikely you'll actually have those four units for their four units at the same time, which is definitely dumb.