the DMCA would still apply. they could file a DMCA against f-droid too. while f-droid is more likely to fight back, if the DMCA is upheld, they would have to comply.

you are not wrong, and that's why apple is being forced to allow alternative app stores. forcing them to abandon checks is not what the majority would want. instead eventually there should be ab appstore choice just like the browser choice that was pushed for some time.