I can absolutely see why Airbnb says this, as their priority, quite rightly, is to support guests you can no longer accommodate whose travel plans will be disrupted.
Were they not able to help you when you contacted them on their social media or through their website? @Olivia240
I do appreciate it must be frustrating not to be able to reach them by phone.
According to their terms you will liable for penalties as Airbnb will say you should have blocked out longer term dates when you put your house on the market so you only took shorter term booking you knew you could accommodate. However you may get a customer rep who will be flexible so worth a try.
I agree that in the meantime do alert your guests as soon as possible so they can try and book an alternative.