While I don't like google, what if I worked at Google but on a team that was doing good (like Angular or 'Project Zero')
I think Mozilla is trying to remind techies to think about ethics for this exact reason: a lot of us have this weird mindset where, unless we can define something with mathematical precision, then it doesn't exist and we don't have to worry about it. This is an incredibly unhealthy way to think about ethics, and it's one of the reasons why our field is sliding towards a bad reputation.
The GDPR does a decent job in this regard around privacy and data use. Can we write a similar document to GDPR around other ethical concerns?
I think it's fine to try to raise awareness of this issue simply as something that younger folk/people starting in their career should consider, if they haven't already. But yes, if they do consider it, also try to get as much information as they can before making decisions. Also I don't agree with pointing fingers at certain companies simply because that's a popular thing to do, you need a lot more data to back up statements such as "big company X is evil", it may take months or longer to go through all that data and get some objective answer to the question. Otherwise we're simply doing gut/feeling based selection, there's nothing inherently wrong about that but we should admit it to ourselves then.
What's most important is finding out the core business models your company is aligned with, and who they work for. For example, if you thought Google was a fundamentally evil company (I'm not saying you or I think that, just an example) then by working on Angular you'd be helping to legitimize Google as a business that does a lot of good things. This will ultimately make it much harder to build a popular movement around stopping the evil Google.
You can see this play out in real time right now as Palantir and ICE try to rebrand as companies/agencies that sell/use tools which combat child trafficking. This may be true, but they also terrorize immigrant communities and must be stopped.