[rndgermandude]

The http/2 stream is multiplexed over a regular tcp stream. At least some push HEADERS and data was most likely already send over the tcp stream, and is most likely already a few hops away from the actual server. By the time the server actually gets the first http/2 RST_STREAM(s) a lot of data from multiple useless pushes could be inflight already. At this point you cannot just close the http/2 stream to avoid data being send. You can only either RST the entire tcp stream and kill all multiplexed http/2 flowing over it (avoiding some data transfer), or accept the data that arrives on your closed http/2 streams and send it in the direction of /dev/null.

Server push, as opposed to preload/hints, only makes sense when you know a) a client will absolutely need the data and b) you're reasonably sure the client does not have the data yet (e.g. data that is uncacheable).