Unfortunately some are more expressive of enmity than others. Don't know that it's something differentiating various fanbases (e.g., see Marlon Brown threads). However, it's something none of us should be proud of.
FWIW, the problem with JJ's post-NSD switch had a lot less to do with the switch itself than it did with the duplicity of comunications leading up to it. In contrast, 4-star WR Kenny Bell also made a NSD switch from LSU. He switched to Bama which, unlike UT, is a team we play every year. His situation was actually similar to Marlon Brown's except he had been formally committed to LSU. But Bell's switch didn't get raise the conspicuous animus on Tiger boards that Brown's did here. He simply changed his mind. There were some negative comments, but in the end these kids need to go where they're most comfortable. We should all understand that.
However, Janzen Jackson's situation was different. He consistantly asserted that he was "solid to LSU" even as late as National Signing Day. In light of Coach Kiffin's public description of Nu'Keese Richardson's recruitment, and the similarity to Jackson's situation, it appears that Jackson was probably not above board in his statements. Switching a committment is one thing. Dishonest manipulation, if that's the way it went down, is another thing entirely. Hence the fanbase reaction.
. . . . Finally, just for the record regarding this thread, it's title, and the individual who started it, in his short tenure on Tigerdroppings BloodRunsOrange has issued a few "less than classy" comments himself. Pot meet Kettle. I'd guess that's not a total surprise to many here, but worth pointing out nonetheless.
Now that he's signed, good luck with Janzen. He is one heck of an athlete. Extremely fast, good vertical, quick, good hands. He's likely an immediate impact player for the Vols. Congrats!