The Scotland captain was rested for Saturday's victory over Munster at Thomond Park, with Assistant Coach Scott Forrest confirming that the centre has trained fully ahead of Glasgows first home match of the new campaign.
"Yeah, Sione's up for selection," confirmed Forrest to Scotland Rugby News.
"That was a selection piece last week; he wasn't injured. He's trained fully, obviously. I think it's knowing that he played a lot last season.
"This is a big season that's going to lead into a World Cup next October, so there's a big piece here where all of our Scotland players are going to get managed at points.
"We know how important this block is for us, but then it's going to lead into those Nations Championship [games] again, where Sione's going to play a lot as well. He's back up for selection. Last week, that was just his weekend not to play."
Kyle Steyn and Zander Fagerson will remain unavailable for this weekend's meeting with Ulster, although Forrest reported positive progress in their respective returns to fitness.
Both are expected to be back in contention before Scotland's Nations Championship fixtures in November, with Jamie Ritchie on a similar return-to-play timeline.
On Steyn, Forrest said: "He's progressing well; he's probably ahead of schedule.
"It looks like he'll play before the Nations Championships, which is good, but he's not up this week. He’s not back into team training yet, but he is in a good place.
"It's a similar story with Zander. He, Jamie Ritchie and Steyno are all quite similar in terms of timelines. They should all play before the Nations Championship.
"Obviously, we've got a couple of big home games, then we've got Sale and the Champions Cup, which we know is going to be important for us.
"It's probably going to be around then, without putting any concrete timelines on it, because ultimately that last part of their return to play is probably the most critical.
"It's really just how they react when they come back into full training and their return to contact, but so far, touch wood, everything's been positive."