That looks like a post from someone who fundamentally misunderstands the dynamics involved in evaluating value in a startup environment (and likely in business period).
There are too many variables to consider in order to make a generalization like that. Even if you have a firm handle on the financial variables (how much you're earning, what your opportunity costs are, what the company will be worth, etc.), it doesn't at all consider the intangible value. So your friend is going to get 1/2 pay for 1%... maybe the experience alone in being able to evaluate his self-worth in the future or in being able to start up his own company will more than make up for a couple of years at 1/2 salary? Who knows. I'd be willing to bet that this blogger doesn't.
There are too many variables to consider in order to make a generalization like that. Even if you have a firm handle on the financial variables (how much you're earning, what your opportunity costs are, what the company will be worth, etc.), it doesn't at all consider the intangible value. So your friend is going to get 1/2 pay for 1%... maybe the experience alone in being able to evaluate his self-worth in the future or in being able to start up his own company will more than make up for a couple of years at 1/2 salary? Who knows. I'd be willing to bet that this blogger doesn't.