Edinburgh head coach Richard Cockerill is "not actually sure how Stuart McInally is meant to play" after the hooker's yellow card against Glasgow.
McInally was sin-binned for a high tackle on opposite number Fraser Brown in his side's 20-16 Scotstoun defeat - one of five players to be cautioned.
Brown was falling rapidly having been tackled low by Pierre Schoeman. His head struck McInally's shoulder and he was forced off with concussion.
"It's an accident," Cockerill said.
"I feel sorry for Stuart because I'm not actually sure how he's meant to play the game if a guy gets tackled and falls at your feet and you're already in a low position. If he falls into your shoulder, where are you meant to go?"
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World Rugby has introduced more stringent punishments for high tackles and foul play in a bid to protect the brains of players and reduce the incidence of concussion.
In consultation with the television match official, referee Ben Blain opted to show McInally yellow rather than red, taking into account Brown's fall, which left the Edinburgh player with little opportunity to change his body position.
"There was contact [to the head] but there was no intent. It's a penalty at worst," Cockerill told BBC Radio Scotland.
"You want to look after players, you don't want players getting whacked in the head, but I don't know what Stu's meant to do. It's a tough one. I get the framework, but we're getting to the TMO, going through the framework, and looking for a reason to send a player from the field.
"We all know Stu very well, he's not that sort of player, and there was no intent whatsoever. It's a rugby incident, it's a penalty for safety probably, but I've never seen so many cards for quite a clean game, really. There could easily have been more because the penalty count was heavily in our favour."
Despite dominating spells of the match, and leading with five minutes to go in a frenetic final quarter, George Turner's late try denied Edinburgh victory in the opening 1872 Cup encounter of the season.
The losing bonus point leaves Cockerill's men third in Pro14 Conference B, a point behind Connacht, ahead of next Saturday's return fixture at Murrayfield.
"It was a stodgy game at the start, very tight and ordinary. We managed to get some ball and look after it for a while," the former England hooker added.
"In the end, you get what you deserve. We'll take the point and gather ourselves together for next week."