What a richard.
I get his approach, wanting you to build stuff too, but he was such a wanker.
I've done several RPs with similar setups, and first and foremost I start building my own thing first. Something people will be able to jump into without building.
And then I recommend people build their own stuff too, to broaden their options for roleplay.
Fair enough if you've just started and have nothing to rp yet, but at least put WIPin the title, and DEFINITELY tell people you're still building when they join and invite them to build too.
You certainly don't demand that they get building.