Not all phones need to play games and gaming phones don't need to use this type of technology. I would love a phone that I don't need to charge and most people could benefit from one. And for the select few that like to play intensive games on it then they can get ones that would need to be charged.

Though I doubt this technology will be the answer to that want though.

You throttle the cpu with long heavy workloads, just like phones already do due to the significant thermal constraints of the form factor.

A nuclear battery is not actually a battery, it's a generator. Trying to run something purely off a generator is stupidly inefficient because you'd need the output potential for the max load at all times even when on average the load is much lower. You absolutely want to pair a generator with a battery. Even power plants have batteries to store excess power.

If you think a little past the name misnomer it's obvious that this would work by pairing it with a smaller battery to handle spikes in usage. The end result is still the same though, you'd have a phone you'd never have to plug in.