Edit: the vulnerabilities mentioned below were all implementation-dependent; the protocol appears to be fine.
I haven't been following Matrix development too closely, but last I heard, both the protocol and the reference implementation had serious flaws, including gaping security holes. As in, issues that couldn't be overcome without a clean-slate redesign. Did they somehow manage to salvage something useable?
I still think nuclear (probably fission rather than fusion) has a place, at least in terms of materials and land usage. It's just obscenely efficient in terms of energy per resource investment. Solar generation requires square miles of space and hundreds of tons of materials to match the output of a single reactor.
Some quotation marks would do your title a lot of favors.