you just got him yesterday..... give him a few days to settle in and get used to his new environment before trying to handle him.
If you can't get him out of whatever he is sleeping in, get him a glider safe sleep pouch and remove the other thing.
There are a lot of "cute" tubes, cubes, and other shaped pouches with small entry holes that only make things more difficult with new gliders.
The easiest thing is to just not use that type of pouch and use one with a wide top your hand can fit in that is easier to 1 remove from the cage and 2 get the glider out of the pouch easier.
The glider won't refuse to eat or die simply from being alone, if it does there was an underlying health issue going on. Many people and I mean mannnnnnnnnnny people myself included started out with one glider. It's OK! it is easier to start with two sure... because then you don't have to do an introduction. But there is nothing wrong with starting out with one and adding more later on. I started with one and now have 10 between 3 different cages. My first was single for 5 months before we adopted a friend for her.
The main thing is to make sure the cage isn't to small, make sure there are stimulating toys for him, glider safe wheel, and glider safe accessories and of course a good balanced diet. With all those things in place a single glider can do just fine for quite some time alone. Of course spending as much time with him as you can helps too.
Now I realize this is going to sound mean, but truly it's not intended to be.
Why overwhelm an already overwhelmed brand new owner ???
You may not know it but it's overwhelming to be told to get another glider or your current one might die. Not only overwhelming, but untrue unless the glider is ill.
Not to mention the information you gave was incorrect and dangerous because you didn't have or ask for any details that could hugely affect the outcome if they followed the advice you gave.
What if the owner has an intact male ?? ( we don't know if he is or not, it wasn't stated either way ) and it was never asked. Even if you did ask the owner may not even know.
What if the owner, based on your advice ran out and got another intact male figuring they are just going to get along great!?
Gliders are territorial, introductions are not always easy, especially if you are unprepared and don't have a clue what to expect or do if something happens and it goes south.
They can't even get one glider out of a sleep pouch yet and certainly shouldn't be adding a second glider right now and probably isn't prepared to do so.
as I said above, it isn't as simple as getting another glider and putting it in the cage with the current one.
I get it, your intentions are good, I used to be the same way omg a single glider get it a cage mate!!! I had to stop doing that myself.
Yes, MOST gliders do better in pairs but I promise you a single glider is not going to die or starve itself simply from being alone. It will not eat most often because of an illness or being fed the wrong kind of food, it will die from infection, parasites, illness, injuries....... but not from being alone.
The thing is introductions are stressful especialllllly for brand new owners who may now feel they can't ask for advice without feeling guilty for a choice they made and are rushed and scared to death their new glider is going to die if they don't.
. If your going to suggest someone rushes out to get another glider be prepared to hold their hand and help them introduce them properly, explain all the steps, be there for them when they need your help, if you can't do that don't suggest it and scare them into what could be a disastrous situation.
Instead, help the new owner learn how to take care of the one glider they have, the best they can. It doesn't matter where the glider came from or how many they start out with.
This is this owners first experience and probably first outreach for help. It can take many months for a new owner to post asking questions the first time, because of responses like the one you gave.