Not buying it. Have you ever tried to steam bend wood? If you have (and I have) you would agree with me. It takes considerable time to actually cause moisture to permeate the wood. Then, for it to warp, the moisture would have to penetrate deeply into the wood. Moisture in the surface layer of the wood won’t cause it to warp. It must soak deep into the wood.
The warpage is most likely caused by the regular steam and possible liquid water the wood has been exposed to. This is likely a typical situation where a customer doesn’t notice the condition of their property until somebody does some work for them. Then when they inspect the work, they notice the preexisting damage and blame it on the worker.
The good thing about this is you can tell if the wood has been exposed to moisture over a period of time or this was the first time it was wet. Depending on the cost of the repair the floor cleaner may just eat it but if the cost is more than they wish to bear, they have a means to defend the claim
But even better: the plaintiff has to prove the carpet cleaner caused rhe damage. Having worked in construction for decades, I could easily prove if it was new or preexisting damage and I could throw doubt onto a claim if they don’t actually bring in a piece of the warped wood.