I still think it was an extremely risky move with only hypothetical evidence to back it up. Parvati made one female alliance, in CI she floated in normal alliances. And even if Russell was asking for help, buying a VILLAIN, VILLAIN, Vee-eye-ell-ell-ay-eye-ehn's plea for help despite not knowing who he is besides so good they brought him back from the season they haven't seen yet, that's all some giant risk/reward behavior that could have been avoided had he waited til merge to do idol dealings. Maybe they could have swayed someone, maybe not, but had he avoided the risk and kept the idol come merge he stood a better chance at giving the heroes majority than giving an idol to a mysterious villain.
Also, you've not picked up on JT's actions post-merge. When Sandra and by proxy Rupert tell them what's going on with Russell, JT doesn't even CONSIDER it, condescending to Rupert and trying to turn the vote ONTO Sandra, who was most likely to flip. That conveniently gets left out of a lot of defenses.
And yet people who defend JT's move still hop on hurr durr Tyson is a moron thing because Tyson tried to take out Parvati because he HAD knowledge on how Parvati was working and tried to snipe her to do what JT tried to do- secure Russell as an ally. Because of something that WAS unprecedented (Russell going kamikaze and playing his idol on Parvati, which I believe even Parvati in an AMA said was a sacrificial move) he went home, but the same defense JT fans make for JT (had it worked it'd have been an effective move!) can be made for Tyson: had it worked, he still holds swing vote power, and he also can gain Russell as a weapon. But that's still a pretty chancy move with chancy outcomes, just like JT's was on a whole other level. It was fantastic TV but it gets pretty lauded for a giant crapshoot that took risks that weren't in their favor.