I disagree. They're british and they sing high pitch. Thats not enough to make that assumption.
Reasons
-Muse has a PHAT guitar and bass sound, while Radiohead the opposite(clean and simple guitar playing, and it later years: electronic keyboards).
-Radiohead is lyric-based, Muse is instrument based.
-The lyrics differ like day and night. Matt Bellamy sing first person and Radiohead predominantly 3rd person.
-Lives shows.
-Influences(claimed by them) Radiohead : Jeff Buckley, Muse : Seattle Grunge & Pumpkins
.... I've obviously had this argument before.
