Stake's self-exclusion policy, number 9, bullet 1. I think what it says is very clear to me that you should not attempt deposit or place wager, how come it's not your fault where you are the one who deposit?
You should not attempt to, deposit or place any wager on any of your accounts from which you have requested to be excluded during your selected self-exclusion.
Per stake rule, it's the user who is at negligence for depositing money while under self-exclusion, if stake will not return the amount deposited, they should not be questioned because they are just implementing their rules, and rules are meant to everyone, no exemption.