Please, do not immediately assume someone had the worst possible reasons for their actions. I would think they did not mute people for "RPing against their wishes", but muted them as the best possible simulation of the most realistic RP response.
You go to a Royal wedding and insult the marrying Prince, you get kicked out. That's really the most realistic action they could've taken from an RP point of view. Yes, it would've been best if they'd have the guards remove all the interlopers, but I suppose they simply weren't prepared for that, and thus used whatever tools they had at their disposal to create the best possible simulation of kicking them out - muting them.
You go to a Royal wedding and insult the marrying Prince, you get kicked out. That's really the most realistic action they could've taken from an RP point of view. Yes, it would've been best if they'd have the guards remove all the interlopers, but I suppose they simply weren't prepared for that, and thus used whatever tools they had at their disposal to create the best possible simulation of kicking them out - muting them.