Can't you just stop buying airplanes from them?
Edit: Do the downvoters also want to throw the executives in jail for life?
Edit: Do the downvoters also want to throw the executives in jail for life?
If you're an airline of any size it would make sense to have relationships with multiple manufacturers, for the reasons you describe.
They can decrease their Boeing orders and increase competitors orders, to maintain relationships and punish Boeing.
If you single source your your fleet, you increase the odds of something like this grounding your entire fleet, and you don't even have any leverage to negotiate better terms from Boeing.
... unless the risk and cost model they're looking at is that having multiple planes in the fleet increases the risk that spare parts are depleted for a particular model, ground crews aren't sufficiently cross-trained and errors on their part make flights less safe on average than in a monoculture, etc.
It's entirely possible (and for airlines operating a wide variety of different length routes, entirely necessary) to safely operate a wide variety of airframes, but it does entail paying for a lot more redundancy.
Embraer's Boeing deal is being termed a "joint venture" rather than an acquisition, with Boeing getting 80% of most of Embraer's business. Important to note it has been rejected by regulators and shareholders on multiple occasions, and still hasn't gone through.
Bombardier recently was pushed to make a deal to sell its popular new CSeries jet to a JV majority owned by Airbus to get around some anti-competitive trade maneuvering by Boeing to add unfair tariffs on it in the US. That said, important to note they are still an independent company with their own jets in other series. Bombardier CRJs are frequently used as regional jets in the US.
[1]: Technically there are also Russian and Chinese manufacturers but nobody would willingly buy from them today. On the tiny turboprop end of the spectrum there are a few more European manufacturers that make plans like the popular ATR72.
Shouldn't the management of a burger joint that caused deaths due to food poisoning be punished, just because there's a McDonald's nearby?
There is a breach of trust involved in these cases, where the potential fallout is death. That is very serious.
And just stop buying airplanes from them.