If you do it for yourself, then it is spam filtering. If you do it for others, without they have asked for, then it is censorship. As I say - you are free to do so, but be aware what you are doing. The blockchain will be used for other things like money if there is a market for, if you try to filter or not. If the applications are useful they will be used - if not then the problem will solve it anyhow.

If you like, that someone is filtering (aka censoring), then run knots. Hope this answers the question.