Yes that is standard. It should be illegal. They said his resignation, effective immediately, had nothing to do with any disagreement over company operations. It had everything to do with that. He was probably fired or quit in anger over his demotion, due to his (perceived) poor performance.
How they can get away with lying to the SEC and their investors like that boggles the mind - but it is how every company handles it. Firings are all resignations and they never have anything to do with the company or the former employees job performance. Everybody leaves as friends that have the upmost respect for one another and can't wait to work together again blah blah they just want to spend time with their kids. That they just drove their company into the ground is a complete coincidence.
"Effective immediately" is common for VP and CxO level positions. Remember Marissa Mayer quit Google and started at Yahoo! the next day.
You're right though that "everybody is still friends" is boiler plate and doesn't actually mean anything. Especially given how horribly Zynga is doing right now, it seem unlikely that things are going great for the CxOs.
How they can get away with lying to the SEC and their investors like that boggles the mind - but it is how every company handles it. Firings are all resignations and they never have anything to do with the company or the former employees job performance. Everybody leaves as friends that have the upmost respect for one another and can't wait to work together again blah blah they just want to spend time with their kids. That they just drove their company into the ground is a complete coincidence.