He have me two reasons, and I suspect a third:
1. Slightly more flex means better, more forgiving ride
2. The wide internal rim width helps spread load so “these days”, 36 is overkill.
3. He didn’t say but my research has indicated that it is pretty tough finding 36h rims.
Were talking about such a small difference in stiffness here, that you can attribute it more to dampening road vibration and resonance rather than actually softening impacts.
There are so many different factors which determine how durable a rim is, that spoke count is just one small factor . You can build an absurdly strong rim with less than 32 spokes.
How comfortable the ride is has more to do with how well you fit on the frame and how you ride it.