Do your due dilligence...
...and you do yours by RTFA.
I've done this before, and this server was configured perfectly: not on any blacklists, reverse DNS set up, SPF, DKIM and DMARC policies in place, etcetera. (Side note: mail-tester.com and Port25 are great for checking your setup.)
This is absolutely a case of the big guys using strong-arm tactics to try and fight spam. Sure, it might be effective to block 100% of mail coming from mail servers which haven't existed for more than 6 months, but it's also completely unreasonable and goes totally against the ethos of the Internet.
Spam detection is just like any other kind of testing. You can have a very powerful test with almost no false negatives but if you start racking up the false positives then the usefulness of the spam filter becomes marginal. This is especially true of the big email providers like Google, Microsoft, and Yahoo. Have a problem with their servers? Good luck finding someone at one of those companies to help you. They don't care about you and your cute little mail server -- especially since you're trying to compete with them.
A faceless tyrant may be the most terrible kind. But get used to it, because that's what we've got with the Corporate Internet.