I believe he was quite aware the mic was hot. Instead of being an asshat, he could have refused the offered short approach and kept to the pattern and extended... Very un_cool.
Yeah, he still had his "performance" voice on. And note how the transmission ended crisply right after his little performance was finished. I don't think that was a stuck mic.
I don't even think he was particularly against the short approach either, given that after he was given an "extend", he came back and bragged to Tower that he could "put this thing down in 30 seconds..." Sounds like he just wanted to put on a show.