Because maybe they would then have to explain where they came from. I do not believe they migrated into Pa I believe they were introduced. Some I am sure are from captive origins..pets, etc. But not every cat in the wild was born in captivity.. I don't buy that.
If they did travel from outside of the state they would do so from a particular area and more would follow. The reports would show a higher concentration of sightings in the area of origin but that is not the case. Same thing happens with ferral hogs and the such. They populate an area, feast on what they can and move onto the next area capable of sustaining them.They aren't going to bypass good hunting grounds without good reason. They don't travel just to travel. A cougar does have a wide range but only when food,territory andmating dictates it needs to.