A quick change to the /blist UI would be useful. Instead of how it is (just names) you could have it as a list with a reason for /blist next to their name...

Jlahsdf lajkd : RMT
Mlasdf Lasfd : RMT
Some Idiot : Knob
Clowd Stryfe''''' : Knob

Click delete, a small window pops up with checkboxes, you click the box you want to clear (RMT) and hit delete, all the /blisted names under RMT are deleted, but you get to keep the Knobs on your /blist. It could also have a "Delete RMT on log out" option to automatically clear the RMT list every time you log out.

Or we can wait until SE allow plugins, I'm sure someone will create a plugin that automatically /blists RMT's on everyone who owns the plugin's /blist.