Demanding justification for things a tool you got for free, is a bit ungrateful. Why not 'request' or 'ask', you might get a better answer. Demanding things from open source is a pointless venture.
The person you replied to might not be a native English speaker. Demand shares a common ancestry with the verb "to ask" in some languages. Take French's "demander" and you might see why someone could use "demand" in a way that sounds confrontational in English but quite normal in another language.