Tclowers posted that Harris' father essentially made Bruce choose between Harris and Pinkston.
That's the consensus from a couple of reliable posters on TOS (NYC Vol being one). The only thing I know for sure is what JayVaughn told me, and that is Bruce would not accept his commitment. He asked JayVaughn to hold off on making his announcement. Bruce had been telling JayVaughn that UT would love to have both him and Harris. However, once Harris signed, Bruce backed off JayVaughn.
The rest of the story about Tobias and Torrel telling Bruce that Pinkston to UT meant Tobias would sign elsewhere is from NYC Vol's sources, which have been very reliable in the past.
It's an unfortunate situation, but I think Bruce handled it the best he could. He took the best player available. This happens quite a bit in recruiting, where one player will just tell the coach, "Hey, it's me or him." I can't say with 100% certainty that is what happened in this case, but all signs certainly do point to it.
If you haven't seen these quotes from Kamani Young, take a look (per Rivals articles):
Pinkston was originally scheduled to make his college commitment before the Fall deadline but abruptly canceled the announcement. It was widely speculated that Pinkston was going to choose Tennessee. Asked whether or not
Tobias Harris committing to TN effected Pinkston's final decision, Young responded, "That's a better question for Tennessee."
Pinkston opted to reopen his recruitment process but the why's were a bit murky, until now. According to Young, Pinkston was indeed prepared and ready to sign on November 18th but," Communication with that school left some question and doubt. The communication between myself and colleges has always been open. We expect the same in return but that hasn't been the case with some schools." As far as which school, Young says, "They know who they are."
Now that Harris has signed with the Vols, the question becomes would Pinkston still be interested in playing for Tennessee? Young says that isn't a question for Pinkston. "I really can't say, says Young. "That's a question for them."
This just reinforces what JayVaughn has told me. Some have said that Pinkston and Young are just lying to make this look like it's UT's fault. I don't see why they would do that. Pinkston wanted to be a Vol. UT wouldn't take his commitment. Something crazy had to have gone done in the last minute (see: Tobias' surprise visit to the UNC-Asheville game) for it to end up like this.
All in all, Bruce is probably okay with how things worked out.