I don't think its about being upset he's playing them, but rather upset he's "singing" them. Just as people want Morrissey to sing them,, but hate his band playing them...
I can't stand Johnny's singing. I don't have a problem with him, and not trying to pick sides. I went to a show of his and unfortunately it might be the worst concert id ever been to. Music was great but as soon as he started signing.... my brain felt like exploding during Smiths songs. I enjoyed the music, but wanted and tried desperately to block out the singing. I do the same when watch his videos.Whats worse here is its like he's not conveying the emotion of the songs, which Morrissey does. Johnny should just do instrumental versions. That would get me to go see him again.
For those that like keeping score or pitting them against each other, Maybe this is his way of destroying the song lyrics just as some feel Morrissey's band have destroyed the music?
But I don't really mind how Morrissey's band have changed the music over the years. Its always a little interesting to hear whats different each tour. And IMO Morrissey's voice has only gotten better. As for Johnny's versions, while a better guitar player, its almost a bit boring that he plays them almost exactly as recorded. (No need to attack they sound great) Just saying he has the musical skills to do something different with the songs. But maybe he didn't want to be criticized for it. Now that he seems to be getting more criticism anyway maybe he would.