Trying to use a carbon neutral energy source for emergency power is very likely to have a higher carbon footprint overall due to the fixed cost of a rarely used infrastructure.

For example, on a much smaller scale, before leds were so incredibly cheap, incandescent bulbs were more energy efficient overall than alternatives such as fluorescent lights for places that were rarely visited. Think cellars, attics, service closets ...

Perhaps that’s not currently feasible, and thus you can’t ”get there” yet?

>as it gets

It's "as it gets" that's doing the heavy lifting here.

Agreed. And "it" is the real workhorse - is "it" carbon neutrality or datacenter power supply?

Zero reliance isn't currently feasible unless you're ok with constant outages. If you're connected to the grid you're using electricity from fossil fuel at some point.