Nickel 62 (34 neutrons) and 64 (36 neutrons) are the only ones capable of fusing with hydrogen to produce stable copper (63 with 34 neutrons and 65 with 36 neutrons). Others are going to create an isotope of Copper, which will decay to cobalt. Obviously by their claim they're only finding copper.
The problem here is that only 4.5% of nickel atoms would even be capable, which doesn't sound like an efficient reaction medium. I don't understand how a full atom would be capable of fusing with nickel when a single neutron can't efficiently fuse with a uranium 235 atom at a .72%.
What I'm wondering is would there be any energy gain from turning Nickel 58 with 30 neutrons into Copper 59, which decays into Nickel 59, which in turn decays into Cobalt 59. However, this decay is long lived (76,000 years so likely not going to result in any immediate energy gains), but then there's the potential of turning cobalt 59 into nickel 60.
So then you reach the question of does turning Nickel 58 into Nickel 60 net you energy? Also would keep forcing a new proton into Nickel 60 making it Copper 61, decaying into Nickel 61 + proton -> Copper 62 -> Nickel 62 (the highest binding energy) actually work?
Honestly, I think they've found a "potential" here, but it's likely just the potential for exploitation. It's been too long since I've done that kind of math to work out if there's the potential for energy gain, regardless of if their 'method' would allow it.