Apropos of nothing: I'll be honest, my initial feelings about this show were very much of the "he should never leave Tatooine" persuasion. But as time has gone on a number of things have occurred to me that actually make MORE sense if he had been out into the galaxy at some point in the intervening decades.
First off, the obvious one: Vader lives! While he never explicitly says so in ANH, it's clearly inferred that he knows Vader is still around; why else even name drop him? If he'd been of the belief that Vader died in the lava pit where he left him then Anakin would have been Vader for like a day--if that--before dying. It would make no sense. (and no, I don't buy into the idea that Vader is all over Imperial propaganda at the time, that just seems dumb, also how much mass media exposure is a hermit in the middle of nowhere going to get anyway?!)
Secondly, he seems WAY too familiar with Mos Eisley than a person with a price on their head should be. That place is infested with bounty hunters, mercenaries, spies, info brokers and assassins. They couldn't even get from the used speeder lot to the docking bay without picking up a tail. Hell, Han couldn't even leave the cantina before a bounty hunter cornered him!
The only logical reason for him ever to go there is to charter passage off-world in a way that won't draw attention (i.e. NOT on the public star liners.) So he's clearly done this before.
Thirdly, (and I know this is a very tenuous detail) but in the scene where they get to the Alderaan system, he barely glances at the scanner before saying with assured certainty "that's an Imperial fighter." When he went into hiding, TIEs weren't a thing. The closest the newly formed Empire had was a bunch of v-wings. So again, he's probably had some experience in Imperial space, AND been close enough to a TIE to recognise one at a glace.
Oh yeah, I didn't mean to say a non-Force user could never kill a Jedi, I just meant that another Force would have a better chance against them.
Sure in general terms, but it's still highly situational. For example, even for someone like Obi-Wan a non-force user who's an experienced Jedi killer like say Cad Bane would be more of a threat than a poorly trained, and/or inexperienced force user.
Obi-wan is also one of the best defenive Jedi. He is not infallible, but it usually takes a full on Sith to ragdoll him (Dooku). At least with his lightsaber. Without he has to get more creative, like when he went undercover as a bounty hunter.
The Inquisitors should have issue with taking him. But they aren't there to take him. They are there to keep him occupied until Darth Vader can arrive.
I'd say they're mostly just there to flush him (or any of the "big names" still at large) from cover. They're not subtle. They're not sneaky. They're a pack of hunting hounds. Loud and obvious, there to beat the bushes and force the quarry into the open, so that yes, Vader can corner and kill them.