A 21-15 humbling by Tonga last weekend led to former boss Andy Robinson standing down after ten losses in 13 Tests.
Since leaving Glasgow last season, Lineen - who spent six years in charge at the Warriors - has been juggling coaching the Scotland Under-20s with a head of player acquisition role.
Current Scotland attack coach and former Ospreys boss Scott Johnson is also reportedly in the running but in the eyes of Nicol, Lineen's domestic experience makes him the stand-out candidate.
"My concern is that any time there's a vacancy the same names are thrown around, but we've got to work out what we need," he said. "I know Sean wasn't universally popular with the players at Glasgow but what coach is?
"It needs to be someone who understands the game inside out, not someone who is using the first year working out the strengths and weaknesses of our game."
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