I thought this was a potentially strong argument delivered weakly. First, he poisons the well by talking about "integrity" and "intellectual honesty". This is a bad move at the beginning of a speech because it is far too easy to take it such that people with different conclusions are lacking in those qualities. Given his delivery, I suspect that he might actually believe that. It would be better if he just owned that…
Discouraging OO would be the worst thing Scala could do. Its one really unique capability is the fusion of OO and functional: it's a language that can go toe-to-toe with Haskell, yet also one that lets you switch from Java in a weekend. Take away the OO support and you'd have just another functional also-ran. Sadly while the language itself has excellent OO support and Java interop, the community support just isn't t…
My opinion -- and I mostly write Scala in my day job! -- is that Scala is in a truly difficult position. Its OOP (and Java) DNA hurts its FP aspects. If it goes full hardcore FP, it will probably lose relevance (because most programmers can't be bothered with it, and those who can will probably hope for Haskell on the JVM). If it stays like it is and tries to be a "better Java", it will keep losing ground to more practical and "easier" languages on the JVM, possibly including losing to Java itself!
PS: DeGoes didn't sound disrespectful to me, and bear in mind I don't know who he is. He seemed to be arguing out of practicality, not shouting people down. I don't if he is angrier in other forums, but his tone in this presentation sounded closer to a wake up call to me.