You're right down 5 with 2 minutes to go isn't striking distance. I mean no team has ever come back from 5 down in 2 minutes.
Being within striking distance doesn't mean much if you never strike.
Like I said before, the Cavs were never put in a position where they had to either score or get a stop in order to secure the win. The Celts never put that kind of pressure on them.
Based on that, I think you can say that the Celts didn't get totally blown away, but I don't think you can call it close. What's more, I don't think the Cavs were playing anywhere close to the level they reached later in the playoffs.
Put it this way -- I think the Celts got the most out of the roster they had and didn't lay down despite facing a vastly superior opponent. That's admirable, even if it doesn't mean they're any closer to actually winning in the playoffs.