Not only do they see all the horror and suffering that Anubis and the goa’uld inflicted on the universe; the could have done anything… not even helping; rather they never even hindered Anubis
They didnt do shit until he halfway ascended and became a threat to them. And how did he halfway ascend? Oma fucking Desala meddled with the mortals, again. And when a mortal gave up everlasting life and power to un-fuck their mistake, they un-ascended him!
They really took a nosedive in the public relations there.
Oma did all those things. They did none of it. She was literally the only one who ever did anything. All they did was ignore Oma and Anubis and Daniel.
Now when Morgan LeFey was trying to help the gang with the Ori, they gave her a proverbial bitch-slapping.
Though, really, their non-interference was basically an application of the Star Trek Prime Directive. Basically the same kind of thing we recommend when dealing with nature, make as little impact as possible. Its only as cruel as nature itself is cruel.
There's a huge difference with the Prime Directive - although I think it can be horrible too.
The Federation doesn't go around leaving super advanced technology to be found and abused by primitives everywhere. When the Ancients ascended, they just left everything behind, for good or ill, and then refused to interfere when others found their old stuff and used it.
The Ancients meanwhile not only did that, but also abandoned friends and allies, like the Asgard. They could've fixed the Asgard genetic problem, and pre-ascension, they'd been allies, but despite that they were just 'nah, fuck y'all, we're out.'