What I know about the bike (I haven't laid eyes on it yet):
*'02 Yamaha XVS1100
*About to roll over the 30,000 mile mark
Calls for either 10W-30 or 20W-40(?!?), SG or higher, and 3.28 quarts with filter.
It will get a filter change every time contrary to the manual.
Not needed. Filter is over size for the engine, and can easily last several oil changes. Complete waste of time and money to change it, especially if the manual tells you to change it every other change.
I'm leaning toward either a 10W-40 or 20W-50, obviously NOT PCMO. I'm a fan of synthetics, he's not

. But our summers get pretty brutal, it's at 30k, and he's 6'3" 375-390, so I think it needs all the help it can get. He can be convinced if it makes sense.
Sounds like you need convinced, not him. You don't put synthetic oil into a 17 year old engine with higher mileage and unknown maintenance history. Conventional oil is fine and likely preferred. And very likely to offer better shifting performance, in my experience.
It calls for 87 octane (8.3:1), but I'm under the strong impression he should use 91 octane (and 0% ethanol in any octane, which is very easily obtained here).
Run non-ethanol 87-91 octane if you can easily get it. If you are running 10% ethanol, than just buy regular 87 octane. 10% ethanol 91 octane offers no benefits in that motorcycle, at such low compression.
Gear oil says SAE 80 or 80W-90. I'm leaning toward a synthetic 75W-90.
Conventional gear oil here is fine. What gain are you getting with synthetic? The potential for blown seals? No thanks.
He plans on taking it to a very remote area to ride it a few times to get comfortable with it. Just enough to not embarrass himself when getting his license.
Don't drive a motorcycle without a motorcycle license, period. In most states it is an arrestable, go straight to jail offense (no ticket, no warnings, bike gets towed and impounded). They consider it a SERIOUS safety violation and zero tolerance. Go take the motorcycle class first, get the license, and then he can learn his motorcycle. The class is very easy and designed for beginners. You don't need to have ever rode a motorcycle. My motorcycle license class was full of 65 year old women that had never ever ridden a motorcycle and they did fine, with slow patient instruction.
I'm also a Techron fan. He's [unfortunately] a Lucas fan...

Are there any cleaners that can be used?
My experience with older carbureted stuff is that if it runs fine, leave it alone. The second you introduce cleaners into the fuel, is the second your carburetor bowl gasket, needle seat, and/or fuel lines start leaking. I've seen it so many times, it cant be a coincidence. Yes you can over maintain your stuff, and break what wasn't broken before (fix it til its broken).
Rotella 15W40 JASO MA is a very good oil, and likely the most used oil in Japanese bikes.
As to synthetic, it shifts like garbage in the Japanese bikes I have personally maintained. Tried to be good and feed the bike a "higher quality synthetic" and it just paid me back with terrible notchy shifting. Changed it back to conventional oil and it shifts like new.
At the end of the day, its a $1500 bike. He is going to treat it like a $1500 bike. Don't put a lot of money into it. He willlikely sell it within 18 months and upgrade to something else, or decide that motorcycling isnt for him, and sell it. Probably not a long term investment here.
The bike has 60 hp, so its not too powerful, but not a beginner bike either. If he is careful, he should be fine.
25-40 hp is a nice starting point for beginners.