What are your SDR settings? If you're using the out-the-box SDR settings, your average picture level is probably just as bright, if not brighter, than HDR. Meaning panel lifespan probably isn't going to be much different whichever you use.
If you've dropped SDR to a peak of 100-120 nits, then HDR content will age the panel faster, then you have to ask what is your time frame? For someone like myself that upgrades every five years, I'm confident HDR viewing will not be an issue in the slightest.
If you want to limit your content to SDR, go ahead, but it seem a real waste of a good display.