The animation in the article is too fast to see what's happening. The impulse pallet misses the stationary escapement tooth in both directions. During the short period the escapement wheel is moving, it pushes the pallet, giving the balance wheel a push.

Here's a working model in slow motion.[1] Notice the escapement wheel pushing the impulse pallet. Not the other way round.

[1] https://youtu.be/JSNDjuKPdng?t=102