If we supported, the reward should be a guaranteed primary rather than autofill immunity.

Right now queuing support secondary is by far the biggest issue with the new matching system, even worse than autofill, and by addressing this we can indirectly fix autofill.

If someone queues for support and gets it, rewarding them with autofill immunity doesn't make much sense. Autofill would most likely place them back in support anyways. The biggest issue for a very long time now has been that queuing support secondary basically invalidates your primary and you will maybe get your primary 2/10 games, more or less depending on how popular that role is. This causes a lot of people to not queue support at all, even though it might be their favorite or second favorite role. Most of us just don't want to support literally 100% of every game.

If after supporting we were guaranteed our primary for one game, this would at the absolute worse mean we are getting primary 50% of the time and secondary (support/fill) 50% of the time. It would encourage people to queue support secondary, speed up queue times, and give a fair compromise for primary/secondary. It also wouldn't be any less effective than autofill immunity, because that autofill immunity is most likely preventing that person from getting support again anyways.