If you lift weights and take steroids, it gives your body more reasons to need protein, and to use them.
My point about fasting is that prehistoric man did not eat every 3 hours like us, so when he ate, ate a lot of food and protein. The body would not say, "I already have 50 grams of protein in this meal, fuck with the rest".
I do not do IF because I prefer to have most spaced meals, but not because I think about protein synthesis and all that BS, so if someone wants to have 3 or 7 meals, it is a personal preference.