I suspect that Telsa, SpaceX and Palantir didn’t sign because Musk and Thiel wanted to talk to Trump in person, and possibly act as (informal) intermediaries.

I suspect that Telsa, SpaceX and Palantir didn’t sign because Musk and Thiel wanted to talk to Trump in person, and possibly act as (informal) intermediaries. Both have clearly stated they didn’t agree with most of Trump’s comments on the topic (without being crass or litigious) and can reasonably point at comments similar to yours to say that they are willing and encouraged to file a similar brief or join this one.