The simple answer is refuse to seat him. He was expelled for cause, that cause is still valid. If the legislature lets him back in then their authority has been usurped. It’s no different than ignoring a judge’s order and the judge just saying OK. You’ve got to enforce your order or you have no legitimacy.
“The simple answer is refuse to seat him. He was expelled for cause, that cause is still valid.”
I have no doubt that the voters in the Memphis and Nashville districts will vote both expelled members back in. And there they’ll stay.