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You do not need to provide a reason why its non-negotiable.
At the same time, don't use non-negotiability as a cure-all for bad practices. If you say everything is non-negotiable what's the point of getting feedback?
Don't let your feelings get hurt
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The people giving feedback know what they're talking about (just like you do), so be open to suggestions that may exceed expectations. If you were asking for feedback on button placement, and you got recommendations to drop the button entirely from multiple people, take it into consideration even if it may not be what you were planning to do before.
Also, remember, you don't actually have to use all the feedback. So it doesn't hurt to hear everyone out.
You are driving, don't let anyone else take the steering wheel
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Feel free to cut off (be polite is possible) trains of discussion that are derailing things.
Mirko / Steve / Room Leader may point out raised hands if it looks like they've not been noticed. this doesn't mean you have to immediately allow the person to interject if you aren't ready, you can just acknowledge and return to the raise-ee when you're ready.
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