If the tool meets your needs, does that matter? Were you planning to make a meaningful contribution to the source? My assumption is that the vast majority of the people making these comments would have never even bothered to read the code, nevermind contribute to it.

To put it another way, if you're enjoying eating sausages then what difference does it make how they're assembled?

why would it be normal? the code is there for you to look at and use or not. It is open-source, licensed as open source and is very clear about that. Why would you feel that the author(s) should need to specify anything else at all to satisfy your curiosity?

it ships with a SKILL.md file, so if they're trying to enable AI to use it, it's a good bet that they used AI to build it.