That's a good argument in favor of keeping time zones, but it's not why we have them.

The reason we have time zones is because people started keeping time long before fast travel and communication made it necessary to consider what time it was on the other side of the mountain, let alone the world. The reason we keep them is because the status quo is hard to change.

Solar may have been weaponized as early as 214 BCE.

You bring solar weaponry into a modern military battle and see how that works out for you.

Photovoltaics can't really be weaponized, and we can't stop bad actors from getting access to large mirrors.

PVs can't be weaponized because they suck as an energy source compared to burning fuels. Any power source with enough energy density to be interesting is a weapon, just like any engine with enough power to give you reasonable interplanetary travel times is a weapon of mass destruction.

Humanity needs to find a way to deal with high-energy technology if we're to move forward as a species.