It would certainly make more sense to find deice boots on a Navajo. The URL of the link has Piper Navajo in it. However the title of the story says Apache and the pics in the story show what definitely looks like an Apache parked in a hangar. The incident specs listed below the article show the type as a PA-23 not PA-31.
As for the lack of blood and feathers? That dent is on the horizontal stab in a position which I would expect to be more or less directly in the prop wash. I've hit birds and had them leave very little evidence behind. Its not unimaginable that what little evidence a bird might have left could have been removed by wind and prop wash.
Given the nature of what they typically do, I wouldn't expect that most survey operators are all that nervous about competition from drones at this point. So I wouldn't expect the operator is doing anything underhanded in order to bring suspicion on drones. Drones aren't well suited to cover the distances they cover nor operate at the altitudes they operate from.
However, given the nature of the margins aerial survey companies typically operate on, it also wouldn't shock me if there was more to the story that the company operators don't want the FAA to know about as it may bring their own maintenance or operations into question, i.e. the engine nacelle lost a hatch so we quick replace the hatch and then hey look at this dent in the horizontal stab that we have no idea how it happened must of been a drone or something....
