I need some advice (pork butt reheating)

I usually pull it and then bag and vac seal. Then off to the fridge or freezer depending on how long before it's going to be eaten. Make sure you get some of the drippings from the foil and pour them in the bag or container. That way, you will have some moisture when reheating.

I would pull and reheat later. If you have a vacuum sealer, vac seal it after it cools and he can simmer it in the bags to warm it back up. It's also ok in a covered pan in the oven to reheat. Some folks will throw a little apple juice on. However you do it, I believe it's definitely best to pull after cooking (after resting at least an hour). I've never tried cooling, reheating and then pulling so I can't really comment on that.

For that short of time you can get by with pulling it after it's rested in the cooler, putting it in a ziploc bag (I like to add a little AJ) & put it in the fridge. Warm it up in a covered bowl of some sort. Microwave or crock pot. YMMV. Cheers!!!

Pull it after letting rest. I reheat it in the oven sprinkled with some rub, some apple juice, and leftover drippings saved from foiling it.

2 things to remember...cool it fast & reheat it fast. This is for someone besides your immediate family (meaning they can sue you).

For me...I prefer to leave whole, but that opens the door to problem #1. You need to safely cool that big hunk'o'meat quick. If you have a vac sealer, use it. Then toss the butt in a small cooler 1/2 full of ice with just enough water to make a slurry. Once in you can finish filling the cooler with ice. Once cool you can store in the fridge. I like heating the butt whole in the oven wrapped in foil. Be sure to inform them the internal temp needs to get up to 165 degrees for it to be safely consumed. After that they can pull it and enjoy. Reheated butts pull great so no worries there.

If you have that vac sealer, you can also pull the pork once you get it off the pit. Flatten the pork out in the bags and they will cool extremely fast with no problems. I'd still ice bath them, but they won't take long. Reheating the pulled pork can be done directly in the vac bag...just drop it in boiling water. He still needs to get the temp of the pork up to 165, but it won't take long.

You don't want to reheat in a crock pot...takes too long (or I would imagine it does).

To be really safe, you'd be better to cook it, pull it, put it in large ziplocks packed no thicker than an inch or so, and ice them on both sides in a cooler. Layer of ice, layer of bags, and another layer of ice, etc... That should make sure it is brought down quickly so it doesn't spend too long in the "danger zone"