should someone who works on a cement tugboat have to believe they are building a better world. or can they just do their job?

They can just have a job. Now if you work on the tobacco industry, knowing full well the bad side-effects of tobacco consumption and keep working on it then you don't have any morals.

Linking cement production to global warming issues is at least as strong a connection and similar scale as linking Facebook to whatever bad thing you think they're doing, which is to say, a very vague one.

Cement production is not a vague link to climate change. [0]

> In 2016, world cement production generated around 2.2 billion tonnes of CO2 - equivalent to 8% of the global total. More than half of that came from the calcination process.

[0] https://www.bbc.com/news/science-environment-46455844

Cement releases a shitload of CO2. In what world is that a vague link? It’s literally the definition of the issue.