The request is exactly about how to "display the saved stuff into a window" if you don't want to dump it to a file and if the output shall go to the status window.
You can use /haltdef and /aline to a hidden @window, but currently you need to /savebuf @window <file>, then /loadbuf -s <file>.
To the OP:
I think /savebuf isn't the appropriate command for this (you don't want to "save" any lines): /filter already has a switch (-s) to use the status window as the "infile" - and could indeed benefit from a new switch to make it the "outfile".
Or allow the use of all @<window IDs> for in/outfile - this would be even more versatile and would not require any changes to the syntax.
