I think Greg's emphasis on whether the witness discount is too high is a more fruitful way to discuss the issue than filtering, but I don't think he fully takes into account the consequences of adjusting the witness discount (as many of the other commenters in the thread point out).
Greg eats @Murch's lunch in this thread.
https://delvingbitcoin.org/t/bug-spammers-get-bitcoin-blockspace-at-discounted-price-lets-fix-it/327/4
The segwit discount has failed at it's purpose. Let's increase it to free.
That's not really how I read that thread.
I think Greg's emphasis on whether the witness discount is too high is a more fruitful way to discuss the issue than filtering, but I don't think he fully takes into account the consequences of adjusting the witness discount (as many of the other commenters in the thread point out).