I think his point is that the rebels ion bombardment only disables vehicles and shields, which is'nt that useful when their opponents can use proper turbolaser bombardments (which makes sense - why on earth would u only use Ion beams? They do sod all!).
Canon-wise, clones did use Ion rifles at some points in the war, but those rifles in Episode 2 were DC-15s - blaster rifles that happened to fire blue bolts. Blaster bolts can be any colour