It's debatable whether or not that was true, and even if you believed it it was up for another debate whether that security was by design or because Apple's vanishingly small share of the PC market made it uneconomical to write malware targeting OSX.
This isn't to say that Microsoft was doing security properly back then either, they weren't.
>Apple didn't give two stones about security until it became a marketing/selling point
I don't much care. Companies don't have ethics, they have fiscal goals. If Apples fiscal goals happen to line up with my own goals, so much the better.
I would tend to trust a company who is doing something to selfishly support the bottom line way easier than I would trust a company who claims to be doing it for the common good of all humanity.
Google famously started off trying to not be evil and also be a profitable company simultaneously. It didn't work out great in that one of those goals became slightly more important than the other.