These kinds of things are usually about defending the trademark against future claims. If they didn't send a cease and desist then that could be used as eviden

These kinds of things are usually about defending the trademark against future claims. If they didn't send a cease and desist then that could be used as evidence that they don't conduct business in this area and so they can't claim protection. You have to use a trademark to keep it, and of of the ways to use it is to enforce it in cases like this that are relatively inexpensive.