Wow. Junk science indeed. "Unforeseen effects on the brain" so you essentially test in a way that is incomparable to those who are experienced typists?

If you're only using one finger to type, of course you're using less brain activity to control that one finger, versus all ten.

I'm unable to read the actual paper, but from the comments here, it sure seems like they worked backwards from an existing premise ("handwriting is better than typing for retaining information") and found a way to make that "truth".

Edit: Missed the link to the article in the comments. Reading it now.