You don't buy what? They didn't claim that it's impossible to deal with it, just that they won't.
And looking at Sparkfun's site, I see how stupid this is. For one model, both are available: 2 SKUs for technically the same board, one is out of stock. And a notice that buying either might be delayed for a few days due to address verification. Very consumer-friendly.
All others they sell as Ardunios only, and they either make them themselves (and license the US trademark) or buy from the european company, so they mostly sidestep the issue.
