where is the proof that it isn't?
That's not how reality works! You can't expect other people to do the hard work for you. Also, proving the negative is never possible. Prove that it is the case, don't expect others to prove that it isn't.
Along the present, more practical lines, when are my Safecoins going to show up in my Masterchest wallet?
If that's not how it works, how do I access my Safecoins?

You can see the number of coins allocated in the spreadsheet for BTC payments and the transaction id's noted there are progressing as they work on those. I guess when just depends then how far down the list you are.
https://docs.google.com/spreadsheets/d/1r4fv57JDNkW55P5dnwPmHF3rOhdt1Jn5I2DZFuZfmfU/htmlview?pli=1If you made payment with MSC then lookup is
https://masterchest.info/lookupadd.aspx?address=ADDRESSGOESHERE