Oh sorry, I interpreted it differently. Tho it still doesn't change anything, they prolonged investigating this issue for months and only put mayor work behind it when they "pick[ed] up a scent on it". Although they knew about it from day one (one Signal staff replied on the same day the issue was posted).
Yeah but he explained, that they could not track down the bug, without having the luxory of default user tracking and metrics. So what can you do, when you have a non reproducible bug, but limited ressources(and other problems around)? You wait for the bug to show up again and then have more data to work with.
What you do is you tell everyone about the issue so they can take the appropriate steps to protect themselves, whatever that might be (don't send sensitive photos, don't use Signal to do it, only use Signal on iOS, etc.); they did not seem to do that.