KohakuI guess it's kind of nice that they've said SOMETHING. Either way, it's easy to see why they are alienating 6s players, and Robin's grievances with 6v6 is something we've all been pretty aware of as a community. If they get more people interested in competitive and this benefits 6s in some way, great, but I admittedly have a hard time getting excited; I know that the day that competitive TF2 shifts from being a fast-paced, dynamic, teamwork-heavy twitch shooter into being about countering godawful unlocks in hopes of artificially shifting the metagame with more bloated shit will be the day I completely stop giving a shit and move onto fighting games or something. I just don't see any merit in highlander, even though valve and the pubbies might.
I think the whole point is to prevent the game from having godawful unlocks that you have to counter. It just gives more people a voice about which weapons have problems so that valve can fix them. I can't imagine this ever hurting 6s in any way. If they somehow manage to change one of the currently whitelisted items in a negative way, you could always just ban it in the league and play a bunch of these lobbies, banning it each time to show valve your disagreement.