It was a private matter, they were not upset. They were a microsecond away from publicly stoning him. He didn't have to tell them. He was under no obligation to do so.
Portia should show Ric a modicum of gratitude for not focusing on who altered the lab results. That is exactly where he was headed. As Ava said, it took her all of 3 seconds to figure it out. Ric is smart. If he bothered to look into it, how hard would it be to flush out Portia? Ava promised to handle Ric and she did.
The other good thing Ric did was not encourage or even mention to Heather that she has grounds for a lawsuit against GH. Portia was acting out of fear for her daughter--but her actions put the hospital at risk.