Formally, anybody can object against a granted EU patent within 9 months.
Looking to Piantelli's claims not only pure Nickel but also Nickel alloys
are applicable.
So, it's basically impossible for Rossi to claim Piantelli's setup cannot
work.
Even stronger, Rossi's catalyzer is possibly related to applying Nickel
alloys.
So, e.g. a NiCu alloy has copper as the catalyst.
Why do I think Rossi's catalyst is the copper in an applied Nickel alloy
powder?
Think of Celani. Think of the large percentage of Copper in the 'ashes'
that Rossi made avalable in 2011 to the University of Uppsalla.