You should try it if you can. Yes, helmet removal can and likely will dislodge, but it's not obvious that just the act of using them with a helmet on will cause problems.
I've worn them with a helmet and they only fell out when I tried to take the helmet off. As long as I look for them when taking the helmet off, they're no different from checking my regular headphones.
Most things I bring mountaineering - especially - most especially electronics are tethered in some ways. It may be too risky to buy an iPhone just to try this out, and I'm doubting anyone's gonna let me borrow a phone and a pair of these. regular earbuds are inexpensive, and if you lose/break them, it's not the end of the world. Airbuds are... $150. For something that can be easily lost.. yikes.