I see no problem in this. We need writing permissions to /usr/local to finish our migration (as we always did). Once you finish the migration we (hopefully) never write directly to /usr/local again.
It was a compliment, as mentioned in other comments. I love the fact that it just doesn't error out, it offers a fix right there. It also humbly offers to surrender the rights to directories it no longer need. Coming from recent Dropbox helper agent debacle, I truly appreciate the philosophy behind this and applaud the team.
I think princetman was being sincere that he loved the experience. homebrew went to the trouble of telling us that we could restore the default permissions to /usr/local, that's nice.
I'm fairly certain you misinterpreted that. He was complimenting the smooth process.
Sorry, I probably failed to notice the "Thanks Homebrew team. <3" part first time round.