I agree with your skepticism about the deal, but not because of taxes. Handling the taxes in a situation like this is a pain in the ass.
The odds of any startup succeeding in any business climate (let alone ours) is low. As employee #1 in the company, you'd want that $2k to be getting a founder's multiple. I don't know what that number is, but my mind jumps to 5-10x. So each time you're getting $2k worth of stock, you want it backed with a story that in 2 years makes you $10-$20k.
The question in this post doesn't contain any numbers (revenue, projections, go-to-market, funding plans), which makes me think that conversation hasn't happened yet with the founder. So what I think is, taking this deal is basically shoveling $2k/mo into a black hole.
I've been in this exact situation twice. I accepted the deal both times. The first time I came out about $20k behind where I would have been with straight salary. The second time, my "investment" made a little better than 25x, which set me up for my own first startup. So it's not like I think this is a rip-off; I just think you're leaving too much up to chance.
Finally, I don't like how Denny is wording this response. $60k/yr is a healthy pre-revenue startup paycheck. It's not rockstar comp, but it's not a rip-off either. If you're getting solid W2 wages, I think it's hard to say that the business "owes" you anything outside of what you can negotiate.