Yeah basically I'm waiting for Kelly's new episode, about to be released. The previous one "into thin air" where Brightan is interviewed
Brian Shaffer Dead or Alive gave me some new vague hints as to why Brian ditched Clint the way he did. So IMO he wanted to vanish, at least from Clint , if he planned to vanish altogheter from his life I'm not as sure. But it could be possible, since this case is an open book with different scenarios who am I to conclude the right theory.
So continuing on the vanish from Clint assertion, Brightan said they talked with Brian about accompany them to Amber's car that was also parked in the garage.
They go outside in the hallway , as seen at 1.55 with them and after Brightan visit to the toilet perhaps a look at watch made him realise it was time to leave then and there. With Clint exiting from the bar the same moments he took the alternate route behind the door and into the construction area and turning his phone off. If he planned to finish off the night with the out-of-town friends he
absolutely didn't want Clint to join in. So ditching him and not be seen was his 100% goal when leaving the UTS.
Since everything seems to scatter at the 02.00 am mark when in fact the Bar closed at 2.30 suggests there was something going on for Brian hitting the road fast and Clint and Meredith wanting to leave the bar. With the new hints, the gather up at Brian's apartment could be that exclamation mark.
In that wake of events perhaps there was a pre-arranged meeting at "around" 02.00 with a companion at Wendy's for a smooth pick-up, that person or group could have themselves been out to other places, and communicated with Brian about that ealier in the day or evening or in the bar. I'm not to familiar with the area as I said but since both Meredith and Amber parked in the garage, there couldn't have been tons of places where to park a car. So from there he could have been either picked-up and things went sour or they weren't there and things got sour, or in fact he continued up the N Pearl Street as you mention to ultimately make it home with the same goal in mind not to be seen by Clint somewhere along the way and then things got sour. Heck, for what it's worth the same ideas could be applied to see him run-away from his life altogheter, unseen. So that's why this is the case it is....mindboggling