Do they have those things at IMSI? To my knowledge, they can receive food packs from a national supplier, but IMSI has only the basic packs. I would be very surprised if they allow fresh fruit at this level of incarceration (they don't allow it most jails and prisons because the prisoners use it to make fermented beverages).
The IMSi policy manual limits how much inmates can use in commissary when they are first year. It can take a year or two to get maximum commissary privileges, although they might be able to get the approved commissary packages (not tailored to vegan diets, so he'd have to trade with people which, again, won't be his privilege for a while).
When he gets to Gen Pop, or more unrestricted privileges, he might be able to eat fruit or have fruit juice while in a common area, but I'll be very surprised if they allow it in his cell, which is where he must stay for now. For probably six months. If he were in a regular prison, he could even work up to being allowed to use a prison kitchen and cook his own food (and order more things). He's under top security at a maximum security prison.
Here's what those prison packs look like:
www.accesscatalog.com
If you try to click through to see what you can send to IMSI, I don't think they're listed as a possible recipient. In addition to these snack foods, if the prison were enrolled in the full program, they could get fresh ingredients (like those boxes we all can order for ourselves).
We can probably lay bets on long it will be before Fruit Cup works his way up to a transfer to a less restrictive institution (I put my money on "never") or even to be allowed to work in the IMSI kitchens (again, betting on "never").
I find grim satisfaction in learning that he is going to have to eat meals based off of what all other prisoners get, without much or any fresh fruit, nor fruit juice, nor avocados.
IMO.