That's not a reasonable method, they need to add a "Report RMT and blacklist" below the blacklist option.

With this they also need to:
-allow blacklist for players offline, to get around the tell and dash
-mute accounts from tell/shout/yell that hit a report threshold pending GM appeal
-scale the threshold up for accounts that have been around longer, more levels, progression in quests, etc
-have a GM verify the chat logs for long term accounts that hit the threshold
-have a system to punish abuse of reporting