Every casino said one can't have multiple accounts but do we have any restrictions for one account for multiple persons? I guess it is allowed unless you are selling the account from one to another which is against their terms.
But no, please don't that is asking for trouble and you should never trust anyone with the money because everyone got a hidden side that we don't know and we might get caught in the middle of something.
This is what me wouldn't encourage anyone out there to start sharing their details especially to that which involves money and you could leak your details to without knowing a day to come his friend could be that monitoring him and whenever he noticed any serious winning then there could be a strict restrictions to the said own of the profile.
Of course casino do prohibit using of multiple profile to gamble, instead it would be that his friend create his own account than to come sharing details to use which very bad and is not a wise decision.