Ryan, filling in for injured skipper Toby Nankervis, struck opponent Port Adelaide's Jordon Sweet about 80m off the ball in the Tigers' 42-point loss on Saturday.
The incident was assessed as intentional conduct, medium impact and body contact, costing Ryan a match.
It resulted in a free kick at the top of the goal square and cost the Tigers a goal at a crucial point in the third quarter.
Richmond coach Adem Yze was pleased with Ryan's attempts to make up for the blunder, but lamented the costly incident.
"You can't defend behind undisciplined acts," Yze said.
"I'll cop it if it's an execution error and we're just not as good as them, but when it's something like that they can just crush your spirit.
"He just came in then and apologised for it."
Ryan was playing his first AFL game of the season after overcoming a plantar fascia problem.
"For a young ruckman who hasn't played this season, and just half a game in the VFL, he was really important for us," Yze said.
"His response post that (striking incident), the next clearance, we won clearly, and that's what I want him to really focus on.
"He needed to pay back the mistake, and all I can ask for is that next centre bounce, to jump in hard and pay it back 10-fold."
In the midst of a personnel crisis, Richmond were already without injured talls Nankervis (hamstring), Tom Lynch (hamstring), Harry Armstrong (foot) and Tom Sims (elbow/foot).
Key backs Noah Balta (hamstring soreness) and Josh Gibcus (soreness) have also joined their  extensive injury list.
Mykelti Lefau and Ben Miller could also offer a hand against physical Giant Kieren Briggs, while 208cm Hayes-Brown looms as another possibility.
The 25-year-old, who spent time with the NBL's Perth Wildcats, impressed with 22 disposals, 11 clearances and 19 hit-outs in the VFL against St Kilda on Sunday.
Meanwhile, Sydney's Angus Sheldrick has been slapped with a one-match ban for his forearm to the head of West Coast defender Reuben Ginbey.
The incident was assessed as intentional conduct, low impact and high contact.
