The veteran was one of three players on the books last season who have yet to agree terms on new offers made at the end of the campaign.
Striker Peter MacDonald is still considering his options, while defender Andy Graham turned down a new deal to join First Division newcomers Dumbarton.
And Ton boss Moore concedes that Young, 32, right, now looks set to follow suit as the strain of travelling from his family home in Aberdeen seems too great to overcome.
Moore told the Tele: "I think Derek is one that has maybe passed us. The problem for Derek is the travelling he was having to do.
"It doesn't look as though that is going to change, so from that point of view I don't think that will be going any further.
"It could only really change if his travelling arrangements altered dramatically and I don't think that will happen. His kids and his wife are still up in Aberdeen.
"Big Andy is away to Dumbarton too. We were hoping he would still come back to us but that's not happened - best of luck to the big man.
"He had a couple of injuries with us; he fractured his cheekbone in pre-season then broke his foot so that didn't help him.
"I don't think the Morton fans saw the best of him but he is a genuine lad. He had a good offer he felt he had to take and we can't complain about that."
But having returned from a family holiday on Wednesday, Moore has already set his sights on adding to his squad.
Deals have already been agreed with five new faces - including midfielder Stephen Stirling and full-back Willie Dyer.
And the Ton boss is ready to kickstart the club's recruitment drive as he seeks to bolster his personnel over the coming weeks.
He said: "We are looking to talk to a couple of players as that is me back from holiday now.
"We are still in the process of looking and we've got to get things done, and get a couple of players in quickly."