A little late.
Without a doubt. Why would that be, I wonder? Cynics would say Walker is maybe making a late surge, and DeSantis wants to capture some of that himself. Others might say too many people were questioning why DeSantis hadn't done more, and so this was a late checking of the box to say he did endorse. Either way at this point the impact is likely minimal.
If he hadn't weighed in yet, I believe he should have committed to Walker before now. Georgia is a neighboring state, and a simple, informal endorsement long ago would have been good for everyone. Maybe that did happen and this article title is bunk, too, but I don't know the answer and would have to look into it.