I found this a pretty interesting and useful way to look at this.
One additional factor I would love to see: situations where one person is coming on a "late" cofounder (e.g. a basic product has already been made, e.g. with outsourced Eastern European developers, and there is some minor traction).
I actually came into this situation with my current startup. My partner had the MVP built by contractors before I came on. He is completely BD/sales, but he had a close advisor who helped him get the product built.
Honestly, this is kind of a nuanced situation. First of all, it depends how long the first guy has been working on the project, and whether he was doing it full-time or on the side. Also, it depends on whether the MVP has product/market fit, or whether it needs to pivot and be re-built before it is really what the customers want.
Overall, without knowing what weights this "calculator" assigns to various variables, it is pretty much useless. Also, as much as technical founders want a formula for everything, equity split comes down to a negotiation (especially if founders come on at different times).
One additional factor I would love to see: situations where one person is coming on a "late" cofounder (e.g. a basic product has already been made, e.g. with outsourced Eastern European developers, and there is some minor traction).