I don't like the idea of providing it. But in the USA each time I receive a shipment via UPS I have to provide my SSN before it'll clear customs. I'd much rather provide a business tax ID, shield my SSN. Bitmain could be requiring this so what they ship doesn't get held up.
Why do customs care about a computer box which is only made in China? Its not like a plant, disease, or counterfeit issue.
I order hundreds of dollars worth of small Chinese stuff on ebay. Little wires, testers, etc... Never had to provide such evasive information.
Only time I had problems with customs is when I ordered from Bamboo seeds from India. I would not think they would have a problem with electronics considered how much volume moves via Ebay alone.