~~BPR. This could have been handled better but I don't think that the admin was powertripping.~~
EDIT: I'm changing my take to YDI / UDI (user deserved it). See discussion with the admin, his usage of power was 100% justified.
IMO what Philip did wrong:
- the issue was in a single community, so he should've let that community's mods handle it. If the user was doing this shit across multiple communities it would be different.
- lack of transparency on what's considered [un]acceptable behaviour for ponder.cat users. A single "be nice" would be enough to justifiably get rid of Cat.
- direct escalation, like OP said. Philip's initial comment lecturing Cat doesn't sound like an admin speaking officially; but when he does, it pops out of nowhere.
In the meantime, look at all Cat's replies in the linked thread: the user is not just being spammy, they are being uncooperative, belittling other users, and passive aggressive. This sort of behaviour should not be given a free pass, and I do think that, if Philip dug across Cat's post/comment history, he would find more reasons to ban the user from his instance... at least if his instance had some rule against poor behaviour.
Internet etiquette has dictates for dealing with undesirable yet not rule-breaking behavior that was just ignored here.
A lot of those dictates boil down to "report, ignore, move on". Reporting would do nothing, and ignoring would be bad advice - because bad behaviour tends to spread. Eventually you aren't just blocking a single person, but a whole lot... or leaving the space because why bother. As such, users in communities with lax moderation tend to monitor each other's behaviour a bit, and this is not a bad thing.