Honestly, it's not a good look for them if they tried to order him into quarantine 18 days after his exposure. I can't defend that based on what I've read from the Amazon supporters here.
But a strike, right now, is not the answer. It's just pouring gasoline on the fire. Counterproductive at all levels. Labor organization is all about picking your battles, and this is the wrong fight in the wrong place at the wrong time. His beef with Amazon needs to be settled in a courtroom, not on a picket line.
The only worse thing he could have done would be to try to lead a strike during a world war.
Did you read the article you linked to? Employer-provided insurance had nothing to do with strikes or unions. It became popular as a way to improve competition in the job market in the presence of wartime wage controls.
And it's arguably a terrible system that we're still stuck with today, with the effect of handcuffing productive people to their desks in dead-end jobs. We'd be far better off with universal coverage that's not tied to employment... and yes, that means better-off economically.
Its a shame they didn't seek your approval to make sure it was the appropriate time to strike, when the least amount of people would be upset, after all strikes are definitely not about inconveniencing people.
Perhaps the workers should just continue to allow amazon to get away with exposing them to covid-19 with no notification, for the greater good.
We have these things called "courts" that are well-suited to addressing complaints like this one.