You can't put conditionals in a notice (or at least it didn't seem to work for me), and there doesn't seem to be any way to negate a condition. I did try setting up a blank notice for that style and then setting the existing guest notice to show if criteria didn't match my blank notice, but then I got a blank yellow box.
Anyway, I already had this product that adds a "day of week" criteria to notices, so I threw in a few lines to add a "user is browsing using style other than..." criteria which I think will do what you want. I'm attaching it here (I may get around to releasing it some day

).