Sometimes some comments are taken a tad out of context. For example, when U2 had a particularly bad attendance show on the PopMart tour (about 19,000 in New Orleans), Keith Richard declared that "U2 has no audience".
At the time, some of us - myself included - were a bit offended. After all, even the Stones don't sell out all shows (and had some "problems" selling out a few shows in 1997 as well). However, later, Bono recorded with Mick Jagger and Bono was on stage with the Stones during one of their appearances in Chicago. So clearly Richard was having some fun with U2 regarding that relatively poor-selling show (as if 19,000 is really "bad" attendance).
As for Harrison, well... his comment was made in 1997. If this were 1987, one could say that U2 might be a "flash in the pan". But by '97, U2 had several blockbuster albums and had been near the top of their game for a decade. Hence, saying that no one will remember them at that point in U2's career is ludicrous, as was lumping U2 with the Spice Girls (who clearly were a flash in the pan, as most of those types of bands are).
Still, artists are entitled not to like another artist. God knows there are plenty of artists I don't like.