I'm going largely on my two-year old memory of press coverage at the time
TJ was the first POI focused on
they searched his car and as best I recall got DNA (though I could be mistaken), and then quickly turned to gathering info on others. At some point I even recall TJ bragging somewhere on the Web (Facebook, Twitter???) that he had been cleared, not that that would necessarily mean anything
but the fact that officers seemed to turn their attention elsewhere indicated to me the likelihood that he was no longer a prime focus (they wouldn't totally clear him, because he might still be withholding info he knows or otherwise be accessory).
At least one of the press articles says "...investigators collected hundreds of DNA samples, but did not name any suspects. Chapel Hill Police did report that at least one person refused to have a DNA sample submitted." Going back through the recently released docs I can't find anything confirming receipt of DNA from TJ although it does seem clear to me that 2 others likely didn't give DNA. I suspect the press quote is either a misprint -- I can't imagine LE actually collected 100s of DNA samples from individuals -- or else it is including all the swabs taken from vehicles and the crime scene as "DNA samples."
Anyway, I understand your skepticism (the circumstantial incriminating evidence against TJ is strong), but it seems to me LE have been looking in a different direction for awhile now.
On a side-note, I wonder what DNA samples collected from the various vehicles show???
Finally, I'll throw out a separate scenario that's troubling me, though unlikely: what if FH had consensual sex that night with someone (perhaps from The Thrill, perhaps not) and then was walked in on by some other suitor or ex-boyfriend who went into a jealous rage -- i.e. the semen evidence is not from the killer, but from someone scared-to-death to say anything or come forward???