Those look like fair predictions. As others have noted, usually when analysts pick a team to win in 7 it means they are more or less on the fence -- especially when they pick the home team to win in 7, which is the safest pick if you think the series is a toss-up.
Hollinger's pick is pretty silly; he seems to think that the Celtics are going to revert to the way they played for the last month of the regular season instead of the way they performed over the last couple of weeks. I sure hope they don't. If they do, though, he's probably right.
I find it fairly encouraging that the two writers who follow these two teams most closely both picked the Celtics to win.