Your analogy happens quite often. Not specifically with Zoho, but if a specific domain is sending spam, your email provider will usually block it at the spam filtering end of it.
It can, yes, but it's invariably because of a usually valid business decision rather than an admin personal grievience.
I get defederating from known bad actors, but these days it's not uncommon to lose access to an instance because admin don't like other admin policies (ergo some defederation over "The_Donald")
I get defederating from known bad actors, but these days it's not uncommon to lose access to an instance because admin don't like other admin policies (ergo some defederation over "The_Donald")