No, it is not completly open source, server is not client is, but client is using google services so… not great you can not have it completely clean.
Adding to that that Moxi is not really friendly to comunity requests, as can be seen on various issues on guthub, I wouldn’t call it prime example of free software.
And truth is that financial side was never clear enough, it can be just someone being careful and understandably wanting to stay anonymous, buy I couldn’t find any lies in linked article. Except title which, of course, can not be proven, but we can allow some clickbite, that’s how this internet business works.