It's just bad code, not a conscious decision to block any specific e-mails. Here's the code of a local construction project's e-mail subscription form:
It assumes all e-mails end in 2 or 3 letters after a dot.
I run into it all over the place. I can't redeem reward points on my Visa card because the redemption 'shopping cart' requires an e-mail to notify you when the rewards ship, and says mine isn't valid. I was blocked signing up for a checking account online because of my "invalid" e-mail, but opened the same account at a branch with the same e-mail address, where they now e-mail my statements.
.info domains have been around for 11 years now, and I can't work around these sites by removing a character.