Not really what was said based on my reading of the court documents. They said he checked a box that he didn't present himself as a professional engineer, when he published articles that said he was. And based on other internet discussions with links to articles, that was exactly what happened and he doesn't really deny that.
The matter of law is "is it right to prosecute someone based on this form" and the appeals court decided it was as you could see in the decision.
Overall I find the court documents seem pretty comprehensive as to why and how it all went down, and they describe him refusing to sign things based on his belief that he wasn't lying.