Reviewing the first posts queue, I run into this question. The last answer seems to have a link for the Firewall keyword, which leads to a commercial firewall (and doesn't have much to do with the answer, by the way, as she's talking about firewalls generally and not about this one concretely).
After opening the author's profile, I saw she has her profile's URL set to the same domain where the link in her answer leads (and personally where I think she works).
Is this considered spam or am I being too rigorous?
The text of the post in question (minus the link) is as follows:
Some Firewall software may affect the speed of the internet because these software filter the incoming and outgoing connection in your pc. If you still have a firewall with increased internet speed, it may be due to the antivirus software you have installed could have removed the spyware or viruses in your pc.
Consider the following clues:
The anchor text for the link is the first instance of the word "Firewall". This is an unnatural choice of anchor text made primarily for SEO, by associating the word "Firewall" (a common search query) with the linked software. A major goal of spam is to boost search engine rankings through spamdexing, so unnatural anchor text choices are an indication of spam. Other indications of spam include repetition of keywords and inclusion of multiple similar keywords, especially when they appear unnatural—these are all intended to manipulate search engine results. See also: Google Search Console help page on link schemes.
[...] creating links that weren’t editorially placed or vouched for by the site’s owner on a page, otherwise known as unnatural links, can be considered a violation of our guidelines. Here are a few common examples of unnatural links that may violate our guidelines:
Links with optimized anchor text in articles or press releases distributed on other sites. For example: There are many wedding rings on the market. If you want to have a wedding, you will have to pick the best ring. You will also need to buy flowers and a wedding dress.
The text is designed to make certain classes of products appear bad: "Some Firewall software may affect the speed of the internet". This unnatural marketing text is intended to make the user's current product appear inferior to the product being promoted. Scare tactics can also be found in spam answers in an attempt to coax the user to purchase the product being promoted.
The text also does not name the product being promoted. This is an attempt to evade spam detection measures as mentions of specific products can be detected by the system. Even in posts that contain no links at all, this can still be a tell-tale sign of spam especially when unnatural marketing text or scare tactics is present.