Even if this were true, you have no right to keep his deposit.
But it's already written in the T&C at the moment (I don't know if this confiscation policy was made since it was added recently).
Thats the thing if its been altered before the incident happen.
Does it really count if those alts havent been used and just focus on the last account he had made? unless if theres abuse that had been spotted then
its understandable on such lockdown.
I think the fact that having plenty of account is against their rules then each and every player should respect it because they agreed to the T&C when they sign up on the site.
This is why we need to read the T&C of every site that we use and understand it clearly to avoid having an issue.
And it shows that the T&C are made on March 16 2020 the issue was recently and here is the T&C that he violated.
3.5. You are allowed to have only one Account. If you attempt to open more than one Account, all of your Accounts may be blocked, suspended or closed and any cryptocurrencies credited to your Account/s may be frozen and returned or confiscated depending on the outcome of our investigation.
And they could return it to the player depending on the outcome so I think there is still a chance that the money could be returned to the owner.
Violation is a violation and the site does really have the right to hold the funds and you are right that it is really important to read up first sites terms and condition before tending to make any actions.
I highly believe that most sites nowadays do really have that kind of rule towards multi-accounting.If that person above had committed such violation then theres no other choice but to take this as a lesson learn for him.