The event:

The precedents:

See the list in this post, Ask Peelsy: How many games for Auston Matthews? but there has only been one cross-checking suspension this season.

The verdict:

The NHL video explainer is available at the link in the Tweet above, if you want to hear it. The gist of it is that the cross-check hits Dahlin in the neck. The play was not part of hockey action to box out a player, it was retaliation for the shoving match that preceded it.