Not only does Reader Mode work beautifully, but, colour choice notwithstanding, the article's CSS styling is sufficiently vanilla that my own enhanced Reader Mode stylesheet (drop caps and a few other fiddly bits) works beautifully. That's often ... not ... the case.
I think it is a good font color. Nice contrast.
Also if you're the sort that cares enough about such things to make a post complaining you should have tools to change them or override per your preferences (e.g. reader mode).
It's high contrast, better than a lot of websites. You'll be fine.