He wants to have the air of the troubled alcoholic genius author who writes in a seedy bar because it's his muse due to his dark past, brooding at the bar where the other patrons leave him in peace as they know he's not to be disturbed when writing his next masterpiece. He clearly wants the attention and the dark reputation, so he writes at the bar instead of in a booth where he would have his peace and quiet. He just doesn't realize he's a nobody without any reputation, and that writing at the fucking bar is gonna invite people to bother you.
In reality he's just a hipster writing a "screenplay" at Starbucks, except with liver damage and obesity instead of veganism and ironic mustaches.
He's a cargo cultist of writing and intellectual endeavours. He sees famous authors writing in weird places, so he does that, without really understanding why. He sees authors writing ironic sequels of beloved classics, so he does that without really understanding why (and that the fad is over). He sees authors being drunk and moody, and he doesn't even need that as a motivation because he's a weak-willed fat idiot and would have been a shitty drunk either way.
The embodiment of Dunning-Kruger midwitism. And also the embodiment of lard.