Barlaser and Roberts came through Newcastle's academy ranks together, but while the former remains on the Magpies' books - albeit on loan to Rotherham - the latter was released in the summer.
Roberts was subsequently signed by another former Newcastle player, Lee Clark, at sixth-tier Blyth Spartans, although a trial spell at Rotherham looked to be in the pipeline after Barlaser put a word in.
Speaking to the Rotherham Advertiser this week, however, Warne suggested that the chances of that now happening are decreasing.
"He's had tonsillitis, he's had something else," Warne said. "He was brought to our attention, He's doing quite well at Blyth Spartans. Dan asked if we would have a look at him. We have a pretty open-door policy here so we didn't mind.
"For now, we haven't been able to make it work. Callum hasn't been fit or well. Until he contacts us, nothing is occurring. The door is still open but at the moment I don't see anything happening."
Barlaser, who impressed in previous loans to Crewe Alexandra and Accrington Stanley, has played 11 times for Rotherham this season.
Ahead of his move to the New York Stadium, Newcastle tied the former England Under-18 international to a new contract, underlining their high valuation of the player.
Have something to tell us about this article?