"In re Biliski" does not require something to be "a product" to patent it. There is no commercial success or commercialization requirement to get a patent. What Biliski requires is that the actual claim language for a process claim (1) is tied to a particular machine or apparatus, or (2) it transforms a particular article into a different state or thing.
There are also equitable defenses of laches and estoppel etc but usually there has to be unreasonable delay and reliance on the delay.
I have not researched this case in particular but it could be that the infringement recently started to occur, or started a handful of years ago and IPAT had tried to do this "nicely" but did not have luck. Maybe IPAT is in the wrong.
In any case, hopefully whoever is in the right will come out on top here.