Well, if the gap would be a problem, it is adjustable, by how the plug looks in the picture. Even if they say "don't adjust the gap".
But, I reapet, I think the ruthenium plugs would work just great as they are, on Punto, too. And the gap difference is due to how ruthenium acts under electrical load. I think it makes a powerful and steady spark and that's what you need, really, on a petrol engine.
If I was to want to fit ruthenium plugs, I would plug them and if they wouldn't work, I would adjust the gap. If they still wouldn't work, that would be it, but at least I knew.
And the cars they are listed for as being compatible, they don't have regular plugs with 1.1 mm gap, as ruthenium gap, the regular plugs gap is about 0.8-1.0 mm, just like Punto.
What price are the ones you found and wanted to buy?