Cloud was more referring to the incident in the lab with the crystal creatures that had killed Sephiroth and Vincent. He didn't know everything about what was going on there and what caused it felt like a simple jump of logic to put the two points together based on what he remembered seeing.

That was of course assuming any of the vision can be trusted.

But he had faith in Ramza, and he gave the other Hero a tight smile and a short nod. There wasn't much more to be said on the matter without them going around in circles.