* YouTube has no liability for incorrect take-downs (17 USC § 512 (g) (1))

* That limitation on liability only exists if they restore access to the disabled material within 10-14 business days of receipt of a counter-notice (17 USC § 512 (g) (2) (C))

https://www.law.cornell.edu/uscode/text/17/512

YouTube doesn't have to host any content they don't want to. However, it seems likely that a court would say "that doesn't absolve you of complying with the counter notice provisions of the DMCA. You can't just say that you don't want to host any content that goes through a counter notice." There are always limitations on the whole "we don't have to host things we don't want to." I doubt a court would let them use that as an excuse to ignore an explicit mandate of the DMCA, but IANAL.

I think the problem is more likely that creators don't want to sue YouTube or have the resources to go up against Google.