Discourse? I don't believe the purpose of all criticism is to encourage action. Cause reflection or provide other perspectives, maybe?

As a disclaimer I can't say I really have an opinion on this as I am almost completely oblivious to MGS and its characters.

Call me crazy, but when you start a video off by saying 'I'm going full SJW', it doesn't really strike me that discourse is desired (Blockbot would suggest discourse is neither wanted, nor encouraged).  Plus, Kojima gave an answer, some people don't believe that answer, find it frail, thin, etc... until proven otherwise, I elect to go by the words people use.  I also realize trying to wrap your head around MGS plot points is an exercise in futility.

Quite sure he was being facetious as sexual gratuity wasn't his objection.

I have absolutely no idea what Blockbot is.

A tool built by some Social Justice folks, that literally blocks 10's of thousands of people on twitter. 

What an absurd tool - not speaking of Kojima nor Sterling here.

Aye, it was designed under the 'guise' of blocking 'harassers', however, it's used as a blanket to silence anyone with a differing viewpoint.  Women Action Media did an analysis of those on the blocklist and found that less than 1% on the list, were actually guilty of harassment.  Hilarious to note, KFC (Kentucky Fried Chicken) a Chairman of the IGDA, and numerous Indie Devs are/have been on the blocklist.

Sex sells. That's why.

It sounds like Kojima's response was a joke.

Has this dude always something to complain abou?

That is the point of his videos. He talks/complains on subject matter. He's not there to talk about happy go lucky stuff.