How do sedevacantists who claim the See has been empty since Vatican II understand the legitimacy of the bishops and priests?

I was recently listening to my favorite Catholic apologist Trent Horn talk about Sedevacantism on his podcast, and he brought up an objection that I’m curious to hear a response too. He said that if the See was truly empty since Vatican II, and becoming a priest/bishop required the laying of hands by other legitimate priests/bishops, then no current priests/bishops except for the ones ordained prior to Vatican II (I think he said it was 4 ministers) would be legitimate. Thus none of the sacramental distributions would be legitimate either. How would a Sedevacantists respond to this?