That reminds me...I've never had one of my snakes bite a vet, no matter what they do. When your snake learns to feel safe with you, it appears to carry over to others.
"Fear-free certified with dogs & cats" sounds like much the same...
And no, at least not for the first couple weeks just let him settle. Right now, it's like he was abducted by aliens...when a snake is re-homed, it's very scary...in the wild
they learn their way around in order to survive (where to hide & where to take shelter), so a new place is confusing & even threatening. What some people do is take an
old shirt they've worn (so it has their scent) & put in in the cage for the snake to lay on & get used to. Personally I don't bother, but it couldn't hurt, it's not a bad idea.
BTW, if you reach into the cage to "tidy up", you are more apt to get bit...

your snake won't connect that with "you" yet, he doesn't yet know or trust you. But it won't
really take long...you have plenty of time once he's more relaxed.