The dev is active on this forum in multiple topics. Here’s his last comment: Project Decorum - Crowdsale (Ended) - #1185 by Seneca
Maybe just post in one of those threads.
I use this search term to stay up-to-date with PDC: Search results for 'decorum order:latest' - Safe Network Forum
Unfortunately they don’t do regular project updates nor marketing, but that’s also what makes them different. Seriously interesting project.