There's absolutely no advantage to Hasbro doing this, so if it's true, it's both surprising and short-sighted. However, I can think of no conceivable reason why they would. In all the 10+ years I've been collecting, I've been outside the US, and I've never known Hasbro to implement such a policy. It seems very unlikely.

What is true in my experience is that some sellers, particularly in the US, don't want to go through the perceived "hassle" of selling something overseas. The way to deal with that on eBay is just to say you won't ship abroad, but some people say they will then change their minds afterwards. Even though this seller - if they are a seller and this isn't just random scaremongering - says about 20% of their sales are overseas, it seems more likely they've decided they don't want to ship to the guy for some other reason and are trying to pass the buck along.

Honestly, there would be a worldwide fan outcry if this were an official Hasbro policy. BBTS and the other online stores that ship worldwide would oppose it and Hasbro would pretty much be forced to back down.