Not a bad idea. Worst case? The product fails, and they sell the domain for minimal loss or potential profit. They could also pivot to a different product with the same name. Might be a hedge for investors not sold on the product.
A domain name is one of the best "real assets" a tech company could own. Reminds me of how Sears department stores owned their property. They eventually spun their properties into a Real Estate Investment Trust (REIT).
It could also be a lie to get attention. It's a plausible price tag.
EDIT: I think they're likely telling the truth. There could be favorable tax implications based on how it's being used (ie a trademark). Admitting publicly the cost of the domain name while claiming the value is different to the IRS could get them into trouble. It's a very smart start to the kid's career. Good chance he's mentored by knowledgeable people.
Maybe interest rates could still go higher