That answer is from an official representative from a product mentioned in the question. The answer is more than just a link. It says the product supports the desired feature in some circumstances. The link looks relevant and non-spammy to me.
I'm not the one who declined the flag, but I would agree with the flag reviewer that determined that the answer is in fact an answer.
The answer doesn't address the portion of the question about how to change the site to make it crawlable. Adding a comment to the answer pointing that out could be a good way to get an edit with additional info. However, answers don't have to be comprehensive to be useful.
Declined flags don't count against you in any way. They are only a feedback mechanism to you from the moderators about how your flags were handled and whether that particular flag was useful for moderators to see.