Like Jeff Schaller, I’m not a moderator...
However to get in touch with a moderator, I think the best way is to @ one of them in the main chat room. terdon is usually quite responsive there, which means he gets to deal with this kind of stuff ;-).
As far as spam goes, I think the practice here is to allow answers which “advertise” a tool the answer’s author is involved with, as long as the answer itself is useful. The spam flag description says “Exists only to promote a product or service, does not disclose the author's affiliation.”, and the linked page explains what’s considered acceptable in detail; I get the impression the disclosure requirement isn’t strictly upheld by the moderators, which is fine in my opinion as long as the relationship is reasonably obvious and as long as the answer isn’t egregious advertising (which doesn’t help much since it’s subjective...). In this instance, the answer’s author clearly mentions his involvement in his bio, which I suppose is sufficient.
It’s worth considering that most of the posts which get dealt with as spam here are clearly spam, utterly unrelated to the question they’re posted on or even the site’s purpose altogether (e.g. face cream adverts etc.). That might “taint” the flag in some way.
I had the same question myself a few years ago after flagging a similar answer and seeing the flag declined.