Charles played the last 4 years of his career in Houton, what are you guys expecting?
Though I'm not sure why he (or other players) would have a vested interest in teams they played for. The coach is different, the GM is different, the players are all different. Who is he "loyal" to? The owner? The name?
I'm not sure this is Houston partisanship on his part. I think he has a philosophical distaste for how he perceives Portland plays, and he purposely takes extreme positions to be entertaining (which is why I don't consider him a credible analyst, and also don't get bothered by what he says).
He considers Portland a "soft, jump-shooting" team. While Portland shoots a fair number of jumpers and haven't played strong defense this year, they're a great rebounding team (generally part of "toughness"), they do get a lot of points in the paint and they're extremely efficient in their jump-shooting...they're not a "jack-it-up" team.
So, I think Barkley sees the Blazers as a team akin to the Warriors or something. He's completely wrong in his perceptions, but that's why he continually sells Portland short.
That said, I'd also say Houston is more likely than not to end the series tonight, since they're at home. But Portland has a perfectly legitimate chance to push it to a game 7, where they'd be solid favourites.