Given that we've seen exactly how little information Signal maintains about its users [0], this seems to me to be alarmist spreading of FUD, potentially to advance the author's agenda of dfederation in Signal, which the developers have already addressed at length already [1].
For example, their assertion that "... metadata is abundantly available here" appears to be patently false, given [0].
For example, their assertion that "... metadata is abundantly available here" appears to be patently false, given [0].
0: https://www.aclu.org/blog/free-future/new-documents-reveal-g...
1: https://whispersystems.org/blog/the-ecosystem-is-moving/