Not sure, why does China persist in supporting the Phillipines, or Israel? They sent military aid during a civil war to a kingdom facing a Maoist insurgency. Classic PRC diplomatic L. Even the US and India weren’t supplying them apparently
http://news.bbc.co.uk/2/hi/south_asia/4469508.stm
Or there’s a fun Quora answer
https://www.quora.com/Why-did-China-side-with-the-Kingdom-of-Nepal-during-the-Nepalese-Civil-War
Xinhua article 2004