If they're at the end of the race with Max set to win the title and a simple swap among their drivers leads to Lando winning, they'd absolutely order the swap. They'd be stupid no to. Oscar loses nothing in that situation (except a meaningless podium).

That would have to have been pre-arranged since no team would ever say that over the radio, so Kimi would've massively violated it by costing Lando 3rd.
Also, that's completely nuts. A Mercedes engined car winning the driver's title does not make Mercedes look good when they're down in 4th and 7th.

If he had wanted to support Lando he would've let him passed into turn 1 in any of the previous laps where Lando got close. He didn't.
In fact, he was clearly against Lando, given that he fought tooth and nail to keep him behind but dove out of the way for Oscar earlier in the race.