If I witnessed it, I'd have already called Panther.
I'd certainly call Panther before I posted his truck number on a public forum. But if I called Panther, are they supposed to punish the guy on my sayso? It's just an unsubstantiated allegation that I can't prove (which is why I certainly wouldn't post such a thing on a public forum). I could have a personal issue with that driver and just make it up that he's peeing on the lot and call it in just to try and get him in trouble.
I really doubt that I'd even call the carrier over something like that. I've certainly seen it happen enough times and haven't called anyone yet. In the grand scheme of things, it just ain't that big a deal.
Back when I was with Con-Way NOW we had the CWN phone number on the sides and rear of the trucks. One night as I was driving up I-55 in Arkansas with the cruise set on 55 MPH with 2 days to get to Kokomo, someone with nothing better to do called in and reported me as driving erratically as if I was drunk, speeding up in excess of 80 MPH and then slowing down to less than 40 MPH, weaving in and out of traffic, and and not being able to stay in my lane. I was also, apparently when I was driving in excess of 80 MPH, putting my bright lights in people's rear view mirrors when they didn't move over and get out of my way fast enough.
Of course, I was doing none of those things, as Safety informed me that the satellite update positions clearly showed that every time the QC checked in for the previous 3 hours I was going between 50-60 MPH, except for the one hour just before the call was made that showed me parked at a Chinese restaurant in Blytheville, but she had to call and check on me, anyway. Said people call in false reports like that all the time.
Then there was the time someone posted online that I was running in the winter in the snow with four bald tires, which wasn't even a little bit true, but Panther saw it, or was called and told about it, and had me transfer my 1500 mile load to a crossdock until I had gone to a place of their choosing and had my vehicle inspected at an out-of-pocket expense of $50. Panther was satisfied with the inspection, apologized for having me do it, but in the meantime they'd given my load to another driver and it was 4 days before I got another load, for less than 300 miles. Panther never even reimbursed me for the $50 like they promised. So they weren't THAT sorry for having me do it.
So you want to be careful about calling in or posting something that you can't substantiate.