ok, i see you only learned every information about purge from alliance player comments only
all sources put casualties as "heavy" and that purge was a "bloody affair" but sure, 5 belfs died...
and they didnt attack anyone, actualy shop owners were attacked by combined SI7 and silver covenant forces for not siding with them agains their neighbours...
alliance also killed or cripled their dragonhawks so they couldnt escape the purge...
as for the "only wanted to arrest them"... yeah, first of all there was zero reason to arrest them, investigation to find the SINGLE person who actualy did something would be reasonable, arresting innocents who have no clue WHY are being arrested and attacked is a bit too much... not to mention belfs do have a bit of experience with being "just arrested" by alliance - Garithos did it and sentenced ALL of them to execution - so why would they expect any different treatment?
for Jaina changing her mind... well if it wasnt for kalec and thrall she would do it so again, she was stopped, if saurfang or someone else didnt start to bitch AFTER the tree was already burning maybe sylva would too...
not saying that sylva was right to burn teldrasil or that it was an achievment, just saying its not like alliance "heroes" and leaders are any better... take greymane for example, and his attack in stormheim, attacking allies in times of war, without any provocation or reason (well, other than vengance) AGAINST direct orders, and that was absolutely ignored after
he didnt even get scolded or what
also i noticed you didnt adress the genocide of taurens in barrens, i guess its better to ignore something you cant justify no matter how hard you try :P
EDIT: just for you info, according to geneva convention following also counts as genocide:
"Deliberately inflicting on the group conditions of life calculated to bring about its physical destruction in whole or in part;
Imposing measures intended to prevent births within the group;"
so basicaly in stormheim by smashing the lamp and freeing the Eyir greymane have commited genocide