Hayes, 34, is yet to make an official decision on his future, but Richardson said the call was entirely up to the veteran.
"I think Lenny would add enormous value to our team and the performance of the team and the guys he mentors," Richardson said.
"He's an outstanding player still and has been enormous for Luke Dunstan and Jack Billings, etc.
"But I do know this, if it can't be done mentally any more because of his body or whatever reason, you shouldn't play.
"With that in mind, it's really up to Lenny.
"I wouldn't talk any player into going on. If they think they're done and they've been into battle enough … I think that's it."
Hayes trained fully on Thursday with his elbow strapped after being rated on Monday a 50-50 chance to play this week.
Richardson said Hayes had responded well to recovery and was more likely to face Richmond on Saturday than not.
Sam Fisher was absent from training and will miss another week after sustaining an injury to a disc in his back in the VFL.
While the defender has been ruled out for this week, Richardson remains confident he'll play in the VFL the following round and is a chance to play seniors again this year.
"He's had five or six weeks of good running [before the weekend's injury]," he said.
"We'd still be expecting him to be able to force his way back into the senior side.
"His form on the weekend was positive enough to suggest he hasn't lost much, but we need to give him a couple of weeks back in the VFL so we're not setting him up to fail from a body perspective."
Leigh Montagna will face the Tigers after missing Sunday's loss to West Coast with gastro while Luke Dunstan is expected to return after a shoulder complaint.
Adam Schneider had 33 possessions in the VFL on the weekend after a foot infection but left the track early on Thursday.
Billings became the second Saint to win a NAB AFL Rising Star nomination this week, following Dunstan back in round one.
Richardson said the performances of such youngsters – as well as Eli Templeton before his broken arm, Seb Ross, Jack Newnes and Cam Shenton – had been a positive in the Saints' rebuilding season.
"Luke for a big part of the year has been enormous for us, given the role he has to play," he said.
"[The nomination] is vindication of our selection of Jack, although it's much more than one week.
"We said earlier in our season we didn't know how much footy Jack was going to play because of his limited preparation.
"He's an incredibly dedicated young man and he's determined to be a fantastic footballer and we're just rapt to have him."
