Not familiar with the GR Monitor,(although I plan on building a pair) but I would think it's a good idea to leave yourself a "de-coupling " option in this type of speaker set-up. In other words, if you're to spike the stand to the floor, leave yourself an option to decouple between the top plate of the stand and the bottom of the speaker.
This especially in regard to suspended floors where decoupling is normally desired either at the floor or between the top plate and speaker bottom. Bottom line, I wouldn't bolt the speaker to the stand. As always, YMMV.