I’m not familiar with Matrix. Does that include some mechanism which prevents “we know you’re running this server and politely ask you to stop”? I understand there are other tools for that but I wonder of the necessity with specific “stacks” as it were.
> Does that include some mechanism which prevents “we know you’re running this server and politely ask you to stop”?
to answer this literally: no. nothing out-of-the-box for that, at least.
but do sci-hub, zlib, and friends have such a mechanism? we've been here before with CFAA, then DMCA. ostensibly, we lost those legislative battles against DRM and copyright. and yet it's easier to access academic articles than ever before.
we have those things above because despite what legislators did, enough of the public is engaged with our goals, or views them as worthy, that it's political suicide to actually enforce on them.
so just do that again, but here: convince the public -- your peers -- that end-to-end encryption isn't for baddies; that privacy is a good thing. that your cause is morally just. build the tooling that makes privacy easy. then use it, share it, spread it. if we get that far, then congrats: whatever the legislators say can't actually hold water.
if you don't buy that, then do what worked for SOPA: voice your opinions publicly. keep the pressure on for months with website blackouts, banners and boycotts. make it a spectacle.
neither solution ends with "write your legislator". if you want to write them, i won't stop you: but that's not where the meat of any of this is actually determined.