Hares can pose a problem for aircraft. In fact anything on a runway as small as a screwdriver can be devastating.
Actually affect the bigger jets more as they can be ingested into the turbines during take off (google Thomson 757 bird strike if you want to see what that looks like)
I suspect the link above is pretty poor journalism. All airports will routinely patrol with firearms. While the preference is to scare wildlife into remaining clear of active areas or to discourage using a range of techniques occasionally if number get to high then it is necessary to reduce the local population. If a large hare (or fox or badger or deer etc) cannot be driven off then it will get shot.