Those suggestions might be alright if he was single, but I'm sure he's going to want to share that experience once in a while.
Focal XS 2.1? (a) They may be "voiced" for the nearfield since they're meant to be desktop speakers, (b ) not sure if they will go loud enough well, and (c ) don't know if they turn sideways well.
Ditto Gallo Stradas (which also aren't active). Though they would be small enough.
Does KRK have anything that small? I'm sure there are lots of actives in the professional and home/project studio market, I just happen to like KRK. And Mackie, but I know they don't have anything that small. Tannoy?
Center channel speakers might work well there, but they aren't usually active -- I.E. two mid/bass's and a tweeter in d'onofrio...d'appolito (or however it's spelled) configuration.
And a lot of professional/home studio/project speakers are designed to be oriented either way.
M-Audio might have something that small.
Just do something custom with a couple of cheap full-range drivers, so that you don't get weird edge effects (doubly so -- once for the speaker ending, and another for the hole starting).