Again- if you think the small retail investors on Robinhood are the ones who drove down the price I believe you are mistaken.

So retail demand is what drove the price up, but lack of retail demand couldnt have drove the price down? Really?

Driving down the price could return that money to them a little sooner- but that doesn't really get them anything so what's the point?

Whats they point?? Didnt you answer your own question? They were reducing the amount of collateral they'd need provide for each share of GME. They were having a transient problem with capital on hand, driving down the price returns capital to their hands because it's less collateral they would have to provide. So they were solving the problem they had with collateral requirements by manipulating the price down, therefore lowering the amount of collateral they had to provide for each trade.

their actions are completely explained by the clearinghouse collateral requirements

You seem to think this justifies them manipulating the market?