You can ask someone to buy it for you using credit card and pay them in bitcoin. Of course they need to be trustworthy of doing this proxy subscription for you.
I do not think this is allowed, as they have a rule that prevents making gifts or transferring them
[1] through accounts and therefore I think they will strive to verify their sources.
You could therefore buy a prepaid credit card from a site such as
https://www.coinsbee.com/, and then use that prepaid card to purchase your course.
I think he needs to ask the support team about that. Quote the following part:
You can't use a pre-paid card to pay for a Coursera subscription.
So I don't think these cards will work because the name and address will most likely be verified.
Contact the support team before purchasing these cards.
[1] learner.coursera.help/hc/en-us/articles/209819003-Accepted-payment-methods