Lets put this into perspective because I can kinda see the logic here.
If you mean that staff should be asking people if they want the person banned for crimes against them then I would say it is a fair request. I used to do this in the past where I would ask if the person felt the person needed a ban, which 8/10 times saved me a bit of time.

But sometimes this isn't going to happen. Some rules we classify as more serious rules with little room for exceptions.

If you meet someone it is advisable to exchange some form of contact. Discord is quite a safe option.

There are rules here so if one is clearly broken then that is on the person that broke the rule.

 

So why didn't you say "That's my friend, don't worry about it". That would be your mistake. The mod was doing their job because you said it was a grief. And if your friend was banned for something you didn't want, go explain to the mod.
I stand by the above.
Please also use the edit button under your posts instead of posting multiple times.