I am glad to read that this writer felt that more humane methods should be used than killing pigeons - and that is the main thing. However, the argument that just because something hasn't happened doesn't mean it won't happen in the future means that we will eventually live in fear of everything. If we don't discount ANY possibility just in case it happens, then I think it's going to be difficult to even leave the house every morning.
Consider this - just because your colleague doesn't spread some massively contagious and dangerous disease to you today doesn't mean it won't happen tomorrow. Similarly, just because we haven't seen aliens attack Earth doesn't mean it won't happen. Can these things happen? Of course - but how likely are they to happen? In the meantime, you're far more likely to be killed in a car crash then you are by some as yet unknown and non-existent pigeon disease.