What is the legal effect if a guardian accepts a bequest of manumission for a wealthy ward when they were not permitted to accept it?

Primary text

If the guardian accepts when they are prohibited from doing so, one possibility is that the acceptance is invalid because they performed an act not sanctioned by the Sharia, similar to selling the ward's property at a loss. The other possibility is that the acceptance is valid, and the resulting liability falls upon the guardian because they imposed that liability upon themselves, similar to the case of maintenance for Hajj if the guardian performs Hajj on behalf of the ward.