"The live shot ... isn't as incriminating as the slow-mo," McIlroy said on Golf Channel's "Morning Drive" on Monday. "It's hard because you try to give the player the benefit of the doubt. He's in there trying to figure out what way to play the shot."
The Northern Irishman believes the incident would have been less of a story if it had involved anyone else.
"I don't think it would be a big deal if it wasn't Patrick Reed. ... A lot of people within the game, it's almost a hobby to kick him when he's down," McIlroy continued.
"That shot does look bad. It's very hard for me to not think that he didn't feel what he was doing. It's a hard one. I'd rather try to give someone the benefit of the doubt, and say look, it was a mistake, take your penalty and move on."
After receiving a two-stroke penalty and eventually missing out on a playoff by two shots, Reed maintained he got a raw deal. He remained adamant that he did not deliberately move the sand, nor did he feel or see the sand move.
With that said, a video of Reed at the 2015 Hero World Challenged resurfaced showing the American performing a similar action in the waste area. McIlroy acknowledged the old footage and admitted Reed's actions were not OK, but he doesn't believe there was any intent to cheat.
"It's almost like it's obliviousness to it rather than anything actually (done with intent) in terms of trying to get away with something. I think it's just his pre-shot routine," he said.