An ICE can burn hydrogen, It needs different injectors, and maybe a different computer program. They may have been talking about that. Hydrogen does not require fuel cells.
Truly green would mean using no fossil fuels at all, generating no waste that cannot be recycled, using no plastic packaging, generating no net carbon. Etc. The Prius is the first baby step toward green.
There's a story about the African army ants that cross a stream by plunging into it. The first ones are swept away by the flow, but eventually the bodies of the drowned ants form a bridge for the others to cross. "And what of the ones who are swept away?" asks the little girl, "They don't even form part of the bridge." And the wise elder replies: "They helped to make a path down to the water!"
We and our Prius will be swept away by the flow. We will not even be part of the bridge. But we are helping to begin the path down to the river.