Of course they should be allowed to receive communion.
“Until death do us part” is a fact, not just an ideal. If someone attempts what would be an invalid remarriage after divorce they are committing adultery. This grave sin is what rightfully keeps them from receiving Holy Communion. The truly pastoral response would be to teach the truth about the lie which is divorce and give those burdened by it the support to live faithfully to the commandments of God.
Depends on who you are. This was and is no problem for the Kennedys who otherwise play at piousness. Or Biden, or Pelosi. If you’ve got the cash or the station, they’ve got Communion you.
if they are divorced and remarried, they are living in an adultrous relationship....no go.