So quote the post where someone seriously suggested we should fire Heupel at this point, because I want to post a nelson point and laugh gif.
This attempt to make any criticism leveled at Heupel's decisions as tantamount to saying he should fired is fallacious at best. Heupel, is not above reproach, and regardless of the time he's been here, he's not immune from criticism when his decisions do not work out.
Heupel made every decision concerning whether or not he wanted to go with a QB on the roster or go to the portal, he went and got Milton, and ultimately it was his decision to make him starter, and it will be his to decide to keep starting him or not. Regardless of his professional reasoning as a HC for doing so, regardless of the eventual outcome (good or bad), every bit of that responsibility lays at Heupel's feet. You can try as hard as you possibly can to divorce him from that responsibility, but you will not succeed, as he was the decider in every single step of that process.