The link you attached predated Surly beginning to sell kickstand adapters by at least five years, which was indicated in the link in post #2 from a different thread (you read carefully). Obviously using a Surly kickstand adapter according to instructions will not void the warranty. If you have further questions, I suggest you go to the source, derby@surlybikes.com, and share their answer on the forum.

I don't use a kickstand, so my opinion about what type of kickstand to use is none, or perhaps a Clickstand-like device.

The purpose of post #2 was simply to share the fact that despite Surly's widely-read-and-argued earlier stated anti-kickstand position, they now sell an adapter to facilitate mounting of a kickstand, a fact not evident to many people aware of their earlier position. The OP left me with the impression that you were unaware of the existence of this kickstand adapter.