The analogy states that the wart is blind, and can only measure two factors of the things it is studying.
This seems unreasonably restrictive, if it really is trying to argue that the Hertzsprung-Russell diagram or the conclusions drawn from it are wrong.
If we were the wart, we could start by examining further our own host so we could extrapolate to the other beings. For example - does the heartbeat and pressure of our own host change and correlate in the same way?
Further, I'm sure we'd be able to measure more than just two factors. For example - what is the size of the being being measured?
We'd also be studying what pressure and heartbeats actually are and what they tell us about the Universe.
(Having said that, I don't actually know what other factors were used to support the Hertzsprung-Russell diagram... any got a good link? [yes I can google, asking for a recommendation])
Get up, a get-get, get down.