@Avi-K, I think you may be confused between your personal dislikes, and things which frum Jews shouldn’t do for a halocho, hashkofo, or mussar reason. The OP asked about the latter; most of your posts relate to the former (“extremely annoying and nerve-wracking”, “found it irritating” etc).
Its a bit like someone asking is it OK to use the eruv in a certain town, and someone replies “you shouldn’t do it because I get annoyed when I see someone carrying”. I agree that if you’re near someone who you know particularly dislikes whistling that it would be good middos to stop. However that isn’t the main niddon here, but whether its OK per se