Some people have speculated that gun store owners would be wary of selling a gun to him based on his looks or behavior.
i happen to be a manufacturer/dealer that has more or less done that exact thing for that exact reason for the person in question. some year or two ago Phil entered my shop and was exploring options to purchase a handgun, and even handled one i had on display. after some cursory questions, and from his manner and appearance, and the way he phrased things with the guy he walked in with, i wasn't really keen on selling him anything and referred him elsewhere.
i used my best judgement and self interest to deny him a sale at my shop. it is because at that point in time i felt it would damage me or my business should i opt to continue a sale i'm not fully confident in the legality of, or because i don't feel like selling to a weirdo with bike tattoos and clothing stolen from a homeless shelter.
despite the cries of alarmists, crazed nutters are not walking into a corner shop and paying untraceable cocaine money for the latest baby-seeking rocket launcher. however a dealer that doesn't discriminate between who he is dealing with is assuming risk he doesn't have to.
if i make a bad sale, there is a non-zero chance i could be penalized with federal prison, loss of assets (money, business, home, et c), or both. it's unlikely, but it's a possibility. so being choosy with customers is one way that many dealers weed out liability as there is no business insurance on this planet that would be reasonably affordable to dissuade it. there is both self interest, a moral obligation, and a legal requirement to do so.
we aren't mandatory reporters and in fact have no real ability to report "getting a bad vibe" other than call in to the BATFE hotline and explain the situation and get a determination that way. given how the feds and certain political groups like to fuck over gun dealers, that's no safety net if something bad happened anyway.
to wit: no dealer will put themselves or their business on the line for a customer that gives them a bad vibe because a sale just isn't worth it. there's plenty of other customers that aren't so risky.
a private sale, between two residents of the same state, typically does not involve a dealer and can be completed on a "handshake". many states have additional rules on this procedure, but even then, Phil may not be able to complete the sale simply because private sellers are often more paranoid than dealers. and those that don't care who they sell too may not be the type of dealer that Phil would even want to interact with because he's inept, a coward, or both.
edit: i'm not trying to rant or anything, i've edited this many times to try and outline my thoughts on the topic in general as well as how it applies to Phil.