Batman: So it turns out Biden cannot be President or do any transition work until the GSA calls it. The GSA is not calling anything at the moment. The question is who controls the GSA...
Biden can't be President until he's sworn in.
Given that Trump hasn't conceded and the states haven't certified the results there is no reason for them to sign the transition memo. It's a storm in a teacup, which won't stop the hysteria of course. Once the stars certify the result the government wheels will start turning for the transition.