What ever you say. Bolt action rifle is just like a pos car you rebuild from frame up. Lot of work changing out a barrel on a bolt gun to change caliber. But you said you did it. Still same rifle.
The “feel” of any rifle is 95% the stock. Dropping in a youth bolt action not going to be same gun. Put a can on end really change it. First just a longer stock will change the balance. I’ll bet looking back one day he’ll wish it was like when he got it new. Good luck!
Do you ever put any thought into what you type because it really does not look like it.
Threading a barrel does nothing but add threads and a thread protector adds nothing. The suppressors un screw and are removable. Changing the stock so it fits is 2 action screws and 2 screws to swap the steel Plate where the mag goes. Yes the rifle will feel different that's the point so it actually fits him.
If someday he wants to change it back it's 4 screws and drop it back in the youth stock. The addition of suppressors is always a major upgrade. Anyone with experience with them never wants to be without them
And yes it's the same rifle. People love customizing their guns and changing things up. It's a huge reason the AR platform is so popular being easy to customize.
Another popular gun is savage for swapping barrels. Anyone can loosen the barrell nut and install a different barrel themselves due to the way the head space is on the bolt.
Some people like standard boring off the shelf crap others want things specifically how they want them.
Barrels are a consumable item with limited life span before being shot out. Yes any rifle will last most hunters many lifetimes and not get shot out and a shot out riflefor target shooter will still be seen as a good shooter by Joe blow deer hunter.
Few cal typically barrel life 243/2000, 7/08 4000, 308/ 6000 rounds. Your average guy may shoot a few hundred rounds with a new rifle then it drops off to less than a box a year so not ever going to wear out a barrel from shooting it. On the other end you have guys shooting competitions and wearing out and setting barrels back each year.
If you don't know what setting back is it's cutting 1/4 to 1/2 " off the receiver end of the barrel and rechambering and threading the end so you can put it back on and not need to buy another barrel blank saving the cost of the barrel blank. on a custom barrel this can generally be done 3 times.
A shot out barrel is due to throat erosion. More barrels are runed by improper cleaning than shooting them out.