It seems like people like to complain about being the center of negative attention more than just blacklisting and reporting.

The game features improvements on blacklisting to address the immediate, and reporting them addresses the longer term.
Do not "try to keep them on your friends list so you can avoid them" or similar. Blacklist and report.

Its ignorant to assume we know whether 'they will grow bored', but if they attempt to persist in some of the loopholes, SE imposes a Temporary Service Account Suspension, which includes " It is prohibited to do this anywhere an expression can be made, such as chat (including Quick Chat in PvP content, macros, and emotes), markers, comments, or titles".

SE FAQ: https://support.na.square-enix.com/f...%20or%20titles.