Respectfully, I disagree with just about every assertion you make here.
> Nobody feels like they "have to" come in on Saturdays
If you list it upfront in your job postings like you're doing here, people will feel like they have to work on Saturdays. Though it looks like maybe your company is just you and a co-founder at this point. If that's correct, it's a little misleading to say that "nobody" feels this way, when the only two employees of the company are the two cofounders that have the most skin in the game.
By setting this policy, you are filtering out a wide-ranging group of senior engineers with families, side projects, and other commitments (such as myself) who will read this and move on immediately (or comment "lol" like another reply below).
I'm not necessarily just "looking for a job that pays the bills," either; I advised, and then directly worked full-time for, a startup that grew from 2 cofounders in the late aughts to IPOing on the NASDAQ about 5 years ago.
Obviously, it's your company, and if it works for you, then great. However if I were an investor in your company I'd have serious qualms with it.