I've never paid too much attention to certificates and have visited innumerable sites despite browser warning that their certificate was not in order.
The topic concerns all of us! Why should it apply to bitcoin users only? The example is signed malware that is related to bitcoin, but it is just an example. Malware is malware and digitally signed malware with a trusted certificate is even worse! IMHO one of the most dangerous and still simple kind of malware is a keylogger. It's not SSL/TLS server certificate related. It's all about installations which are a sort of trusted by the system such as drivers: https://docs.microsoft.com/en-us/windows-hardware/drivers/install/digital-signatures https://msdn.microsoft.com/en-us/library/ms537361.aspx
A current example : CCleaner v5.33 hacked http://blog.talosintelligence.com/2017/09/avast-distributes-malware.html
i agree even if im not a bitcoins user...i dont want any kind malware sitting in my comp i dont know what else it could do.