If Bob and Jon prefer to use a HI FFL anyway, check with the one you select to make sure they have the right paperwork to receive the guns and release them to Bob. Some HI FFLs only accept shipments from other FFLs, others don't mind.
In terms of expense and simplicity, shipping direct is a better option. Make sure to use the proper packaging, markings (nothing identifying contents as firearms on the outside), and service. Handguns have to be sent commercial carrier by non-FFLs, not US Post Office. Long guns can go USPS.
A simple bill of sale from Jon to Bob dated when Bob was an AZ resident ought to be enough. For registration, there's no paperwork like that required. HPD will check to make sure none are on a stolen/BOLO list.
If Bob has his LG permit, then he's already had a BG check. Makes registering Out Of State firearms easier including handguns.
DISCLAIMER: I'm not a lawyer. Anything I post on this topic is in answer to a hypothetical discussion. My recommendations are purely notional and not to be taken as legal advice.
Having said that, there is always more than one way to legally accomplish the same thing without choosing the most difficult path just because "it's better to be safe than sorry."
Do some research, read the ATF and HI rules and statues on this subject, and find what best fits Bob and Jon's situation.
