My understanding is that, under the CFAA, any unauthorized access to commercial servers is a felony (more-or-less; there are some requirements here, but as I recall they're so broad that they basically always apply).

The theory here is that, after breaking the TOS, if you continue to use the service then that use is unauthorized and therefore felonious.

As the EFF notes, previous judges have refused to rule it this way, basically on the basis of "that's insane, even if it is what the law says".

Edit: for reference, the relevant legal bits are here, in section (a.2.C), with relevant definitions in (e.2.B): https://www.law.cornell.edu/uscode/text/18/1030