OK - help me with this question from my Dad - user account names

When we set up his MacPro (he's a switcher) - he put my mom as the user, first & last name - but did her short name as her nickname.

Now they can't create an account with that nickname.

Their concern is that having her first & last name as the Admin account - and if she goes online, that anyone on the net can see that name. Hence, she wants her account to be her nickname.

I told him only if he lets Little Snitch send it....

But seriously, i've never THOUGHT about it, because I assumed that the outside world can't see my user account name. So the question is striking me as weird....

So help please!!!

That is what i would expect - which is why i never considered it..... and kinda sat here drawing a blank when he asked.