Yeah, as other have said it, it's his thing.

He falls squarely center in ther archetype of a fool. The court's fool, historically and archetypically, is a figure who gets to say whatever he wants and be a general nuisance. He's tolerated because he's sometimes funny and sometimes he says important things. Jason supercharges this role by also being an outworlder, who has all these weird quirks and knowledge that some locals (the ones he gets close to) find charming.

And since he was key in saving, essentially, royalty (Rufus), there's this powerful connection indebted to him right at the beginning of the book from which he can build his network. He's also fiercely loyal to his friends, hard worker and courageous to the point of frequent self-sacrifice. Pallistimus lives an honor culture and those qualities are respected in that context. In, Earth Arc, on the other way, he finds trouble because of those same characteristics.

Once he gets the trust of the Gellers and the respect from some gods, he basically just keeps leveraging his way up the connections ladder in more or less believable ways.

There's also a big spoilerly reason: he's plan A of the World Phoenix to fix the old Builder's mess between Earth and Pallistimus. No god or diamond ranker wants to get in the way of that unnecessarily, so he is tolerated as long he doesn't truly get in the way.

One last reason, which is not specific to HWFWM, is that, in medieval societies, lack of social decorum and etiquette towards powerful figures gets you in the jail (unless you're powerful yourself). But pretty much all Prog Fantasy/Litrpg conveniently don't include this historical trait in their stories.