Because he lied about it coming from the Biden administration. Like the constant lies about things that aren't part of the Democrat's party platform to trick low information voters. It's pathetic, dishonest, and immoral. I've always said there are political lies (i.e., puffery) which we've all come to accept (usually in the form of overpromising things), and there are outright falsehoods like "Biden wants to limit your beer intake" and the one about schools being required to provide kids with litter boxes if they identify as cats.
Edit: Polds beat me to it with more specifics, once these idiots mention it, they say it everywhere, and I guarantee you half of Oklahomans come next November will still be saying that they have to vote Trump because Biden went too far trying to limit them to two beers a week.