No, for a few reasons:
1. That would not be an authorized means of contacting them.
2. Unlike Google Cache, which passively scrapes a copy of existing web content, doing what you suggest would involve actively interfacing with what passes for their version of a website API in order to contact members specifically, and even if it were allowed, I doubt it would be possible, given how they have changed the code so much from the stock PmWiki codebase their wiki started as.
3. The rules are that we have to build off what we have, and make from scratch what we don't. As frustrating as it might be otherwise, that's the breaks with forking a website, everything after the fork point is your responsibility.