It certainly isn't proof they prefer TU settings. Why did they hold a vote? Why didn't they take the action you're suggesting earlier? Obviously a substantial amount of people prefer playing Halo: Reach Team Slayer as designed and balanced by Bungie. Enough to keep those settings in matchmaking.
That "vote" was garbage and you know it, for multiple reasons.
-The majority of players DON'T READ THE FORUMS or WAYPOINT. This is pointed out time and time again by everyone including Frankie. The majority of players didn't even know what they were voting for, they just picked whichever gametype and map they liked more, which brings me to my second point.
-Different gametypes and map combos for vanilla and TU choice. How can you have a controlled vote when your options can and certainly did end up like this:
Slayer DMRs on Arena Zealot
TU Elite Slayer on Uncaged
That's not a controlled environment and people's choices could have been for any number of reasons. Gametype? Map? Map and gametype? Maybe people didn't vote at all? It's not uncommon at all to go a voting round where less than half the players voted. And if no one voted at all then the top option gets picked, which was always Vanilla was it not? Would that not completely skew results?
It was riddled with problems and not conclusive of anything so please stop acting like it was.
The vote should have been conducted on Waypoint so the voices of the people that actually know what changes they're voting for are heard.
Besides, I don't think any other game in existence was left in a state of partially title updated. That in and of itself just looks extremely unpolished, like the health pack glitch which got bleedthrough removed from all TU gametypes.