You can add you website to Google Search Consle at search.google.com/search-console. This should help verify the legitimacy of your domain and hopefully Google will take away the security notice.
However, the Transparency Report says that your website tries to trick visitors into sharing personal info or download malicious software, so your success rate may be low. Here’s the report: Google Transparency Report
Yeah, the original post mentions that, and that’s what happens when your website gets flagged by Google Safe Browsing. I’m not familiar with the unsuspension process, but from this I believe a grace period may be offered for the domain holder to (re)submit their website for review in Google and get it removed from the list if Google deems it to be safe.