Jermaine wasn't exactly welcomed with open arms by the others on the safe couch.
I don't think they know how to act around him.
Here's what I noticed and was very much struck by: When Jermaine was on one of the Bottom 3 stools, he reached out to each person who joined him, and none of them acknowledged it. They barely looked like they knew who he was. Eventually, he stopped reaching out, and then one of the guys did acknowledge him. But the two girls practically walked right past him, and one ran to and hugged the girl already on the Bottom 3 stools.
So when the safe contestants failed to greet him or celebrate when he returned to the safe seats, it just seemed like a continuation of the same strangely cold reaction he'd gotten earlier. It was not IMO a reaction to his celebration at being safe. What it was all about, I don't know.