That one tech said he has seen this issue doesn't make it a known issue. That would be like I saying it's a known issue because you posted a question about it. The phrase, "It's a known issue" is interpreted within this context to mean Apple has acknowledged the issue exists, publicly. It's a defect if it's a physical or electronic flaw. These could be considered manufacturing flaws, thus, covered under the warranty. If it's a software issue, then it's called a bug. A bug is not a known issue until it has been reported to Apple where they attempt to replicate the problem. If the problem can be replicated, then it is a known issue.
Apple repairs known problems by issuing a statement in which the "fix" is explained. If there is a hardware flaw involved, then Apple releases a warranty extension for some period of time during which you may have your machine repaired under warranty beyond the normal warranty expiration. When the extension period is over, then the extended warranty no longer applies. However, in your situation, the problem was not a known problem and there was no extended warranty. Therefore, you are not covered under your now expired warranty.
I have sympathy towards your situation but you have been treated fairly. The standard warranty is one-year and the extended warranty, AppleCare+, adds another two years. You could have taken the machine in for a warranty repair "if it qualified for one" but chose not to. Out of warranty can be one day or 45 days, but it's still out of warranty. The only person who could change that, hypothetically, was the store manager. They do have some wiggle room, I've heard, but usually only within 30 days after expiration. It's up to the manager. If you were quiet and nice about the matter, were complimentary and polite, maybe you get a favor. If you put up a tantrum, then you usually get nothing.
Threatening to never buy another Apple product is an irrational choice. You'll go and buy some other manufacturer's hardware along with Windows, but you will find that the story won't be different should the same situation arise again. You'll moan about Windows but it will never be the GUI that macOS is. You could try running Linux which is somewhere between Windows and macOS but there is no Linux support.
Happy Trails to you.