Shooting a .22LR AR-15 "to develop muscle memory"???? Are you kidding me? Muscle memory for what???
Bottom line is that for the cost of a .22LR AR-15, you can get a case of 1,000 rounds of .223 or 5.56 or more. If you can't "learn the controls" of an AR-15 (we're not talking about an XM-1 tank here) with 1,000 rounds of ammo, you are not going to learn it.
Look, if you think they are cool and want to shoot a .22LR AR-15, then be my guest and go for it! Have fun. Knock yourself out. But for goodness sake, stop pretending that you are doing something useful to training with it.