Would you prefer for them to be referred to them as "Cosmic Rays" :) ? To be honest, "Space Particles" sounds less silly and more descriptive. It also emphasizes that they're not generating the muons themselves, but collecting them from space.

EDIT: Though I guess, now that I think of it, it's a bit unfair to refer to muons as 'exotic'. People will typically encounter thousands of them in a day [1].

[1] http://cosmic.lbl.gov/SKliewer/Cosmic_Rays/Muons.htm

[1] "Muons arrive at sea level with an average flux of about 1 muon per square centimeter per minute."