You don't even know what the original discussion was about, so why try getting involved?
The original quote was in regarRAB to Nickelback being put in the 'pop music' section of the forum, Urban then moved it to the Rock section, when asked why, Urban replied 'Because its rock music, being popular doesn't make it pop', and then he used the comparisons of Miles and Black Sabbath, who are both very popular.
If this other poster got his way, both of these artists would be in the pop section, simply because they are popular which is blatantly wrong. Surrell nor anyone else suggested Nickelback is as good or deserves to be be as recognised as Miles/Sabbath/etc. All it had to do with was where the thread was placed.