This little guy will be keeping his nuts for a reason…
Because removing the primary sex organs and the source of most androgenic hormones impacts behavior in what most people view as a positive way.
If you vasectomize a male animal or perform a tubal ligation on a female animal, the sex drive, seasonal cycles, and the behaviors that accompany them will persist.
No one likes the female cat in heat that keeps the whole neighborhood up at night with her meowing. Nor the male dog that gnaws through a fence to escape because a bitch in heat down the road is driving him crazy.
The only reason why someone would keep the sex organs intact, but remove the means to procreate is if they have very particular reasons for doing so.
I know this because I’m one of those people. Female wolves often see neutered male wolves as inferior or useless. I’ve seen big neutered males hen-pecked and picked on by females to the point where they had to be separated.
For this reason, even when we have animals that we never intend to breed, even when partnered with spayed females, we let them keep their nuts.
For wolves, this strengthens pair-bonds and has other health benefits, but we’re the exception to a rule most people shouldn’t break.