Even if President Raisi of Iran abides by that - and he's already said, Iran will spend it as it pleases - it frees up other funds to use for malign purposes.
They don't have the funds. Qatar is holding the money. Funds can only be spent abroad on humanitarian aid. Col made it sound like Biden gave $6bn to the Iranians, that's just what the MAGA crowd are making up.
I doubt Iran spends much on humanitarian aid for Iranians, it won't make a difference.