There's no anything cooked into reality. The very concept of "idea" is human-centered.

But that's a fruitless line of thought in this context.

It doesn't negate the fact there are bad ideas. Heaven's Gate mass suicide was a bad idea (and its justification was patently wrong: no soul was uploaded into the mothership). Bringing feral tigers into your apartment is another bad idea. They are only "subjective" in the most theoretical, I'm-having-an-internet-argument sense; in practice they are objectively bad ideas.

Some ideas -- maybe most -- are neither good nor bad. But again, this doesn't negate that some ideas are objectively bad or good.

Hardcore moral relativism (or is it "ideas relativism"?) is such a boring position to hold. I suspect it's also a dishonest position, in that deep down very few people actually hold it.