I’ll just reiterate this:

Physical maturity=/= maturity or adulthood.

Claiming otherwise is just wrong.

There’s different aspects of what makes someone an adult. The physical part is, in fact, only part of it. That’s why the RAW specified the physical maturity part, because it’s only part of it. Otherwise they’d have just said “they mature ate the same rate as humans.” That’s not what they stated though.