Well, there was a huge TOOL thread a couple of months ago that ended up getting locked. Requesting TOOL for DLC is definitely something that you might equate to beating a dead horse at this point.
TOOL is very particular about their artistic direction. They may not want to have their songs associated with the imagery of RockBand. Custom venues for TOOL? A recreation of their 03 Lateralus stage set would be awesome in RB.
Gimmie a 6 song pack
Vicarious (although not may fav from 10,000 days, would make the best RB song, IMO)