Well I don't think its an error or a typo. I think it is purposeful. Open chord shapes, and relationships between chord types is the point of the lesson. To quote the preface on the lesson page.
"Continuing on now, we have 9 more chords for you three types of chords, Major, Minor and 7th, this time on D, A and E.
As for the last lesson, a VERY useful exercise for you to do is to compare the chords with the same root, for example, play A, A min and A7 and see how they are related. Do that with each chord and you'll start to make connections which will make it easier to remember the chord grips and also help unlock the fretboard (helps for guitar too!).
Where is "B" I hear you ask! Well B is only playable as a movable chord shape (kinda like F on the guitar) so we're going to check them out in a couple of lessons time!"
As shown on the lesson page.
D major: A D F# A
D minor: A D F A made from the major shape by flatting the third.
D7: A C F# A made from the major shape by dropping the root to C.
The first grip you reference isn't an open shape and the second was likely deemed "more difficult" the the basic shape that was included.