It doesn't work in that case either. Bakara says the krogan almost destroyed themselves before the Salarians contacted them. Also, uplifting isn't primarily about gifting technology.
Uplift in that context was giving them the technology to fight the Rachni. You could say that it is a particular krogan problem, as they are so aggressive.Perhaps uplift is the wrong word, I used it because I don´t know a better one.
If we look to history for evidence, we'll find a different picture: when the Europeans reached America again in the 15th century, that had a disastrous effect on the indigenous civilizations, while you can be sure the Europeans weren't in the least interested in letting them acquire their technology.
Seems the scientific community is divided on the issue slowly moving towards factionalism and disease with fatality rates around 95% as the deciding factors for the indians. Cortez won because everyone of their neighbors loathed the aztecs with a passion. The technology bases weren´t so far apart in the 15th or 16th century and before the natives keeled over en masse, the relationship was a trading one. Anyways a 15th century gun isn´t really that hot, horses and mobility were a bigger factor in that regard. I recommend reading "1491" or "1493" by Thomas Mann as possible starting ponts. It would be pretty hard to condense that stuff into a couple forum posts. And I am really not into a debate based on "my school history textbooks say something different."
On the other side of the globe, some Asian cultures attempted to isolate themselves and "stick to their own path", but that didn't get them anywhere either. Then, look at what happened with Japan after they became more open: they went from hopelessly primitive to one of the most innovative countries in the world in less than 150 years.
Considering that the japanese won against the russians 1904 which were considered a major power at that time, you can make that 50 years. The chinese weren´t necessarily against trade at all but getting their land swamped in opium. But yea the chinese totally overestimated themselves and seems they should have better traded their tea, porcelain etc for tech and not silver instead.
So I think the problematic step is *contact* between a more advanced and a less advanced civilization. There may be a case for a "Prime Directive", but once contact is established, the less advanced civilization absolutely needs the means to adapt in order to survive, and that includes importing technology until it has established its own tech base. If it doesn't want to adapt, it'll pay a heavy price, maybe even die out.
Yeah it´s more complicated than Mordin´s short statements, but Mordin´s PoV was from the perspective of the more advanced race who gave the krogans the means to play hardball without considering longterm effects. If Commodore Perry and his superiors had known the future, they would left Japan alone probably.

Mordin´s analysis seems to be krogan only, who blew themselves up with nukes before they figured out that it´s not a good idea and then handing them weapons to blow things up on a galactic level.
Seems that Mordin´s statement doesn´t really fit to the stuff we debate.
I can understand Legion´s PoV, Sovereign demanded a steep pice in return after all.
There's also this corollary: if some non-human civilization gifted humanity with, say, FTL drive technology, do you think there there's *any* chance that it wouldn't be used? I don't rule out the possibility that technology can be a poisoned gift, but once you have it, even if it is a trap, the only way out of it is to master it and adapt - if you refuse, you'll be left hopelessly behind and will likely never get another chance.
The last thing I would give humanity as an alien, would be something that would allow them to move into my turf.