I have updated arch systems that had not been powered on for years before. It was fine. No issues what so ever. Arch is not some flaky distro that breaks if you look away for a minute. My main system has had had the same install for over 5 years now and I regularly forget to update it for months at a time. Again, no issues.
Your average criminal is not making their own and have to trust some third party regardless. Law enforcement agencies have been known to have wide spread honey pot secure messaging apps before.