The higher ground has no meaning to me. In that, I agree with Sabin - they will twist your contact as guilty conscience and regretful of your decision. Or those they confide in will gossip and speculate.
As long as you still send cards, you still have that negative association and link to the bOrg. Like a millstone.
If they wake up, they will soon track you down. They will accept their part in all of this and not hold a grudge, because you were allowing them the freedom to follow through with their doctrines. They will not resent you or resent the years of no cards when it was only ever going to be one way traffic.