That's the point though, it's not just someone doing it that has triggered their defences, it's many - most probably unwittlingly because of malware or even som

That's the point though, it's not just someone doing it that has triggered their defences, it's many - most probably unwittlingly because of malware or even some of those cheap shitty games that mysteriously steal your battery and/or data allocation with unknown background processes. The point is thus: they are receiving enough bad traffic from that range to have determined they need to filter it somehow.