Good communication goes a long way. Just never ever install restraint on the windows as that's almost certainly illegal and could cause death if fire broke out and they could not escape quickly. I would never return to an Airbnb that did not allow me to open the windows fully, even if I didn't feel the need. Never impose risks you wouldn't want anyone to impose on you.
There are many reasons guests open windows, and they probably won't tell you about most if them. This is because some hosts are very touchy and will get grumpy when approached with issues. Usually when a guest opens a window, it's because something about the air quality or temp is bother some or unhealthy for them. Other guests may actually wish to violate rules by smoking, vaping, using incense, cooking in the room, etc. So, the better your communication and the more you provide accommodations to prevent problems, the better off you'll be.
It's reasonable to ask guests to close and lock windows when leaving the property or allow you to do so in their absence. However, if that makes their room too hot or lets it fill with wood smoke from your fireplace, then you need to provide AC or fix the fireplace problem. If there are dust mites, cat allergens, smoke residue or scented products in the room, even from laundry products, remove them.
People open windows for specific reasons, so be sensitive to their needs before setting rules about open windows. Most will cooperate if you're meeting their basic health, comfort, and safety needs.
