> That's a nonsensical definition. By that standard literally everything is political

The definition implies it, yes

> which means the word has no meaning.

I disagree, the "if everithing is X then nothing is X" applies only to thing that are in part defined as negative/contrapposition like being special, tall, a luxury, progressive, conservative, etc. it does not make sense when applied to things like being religious, having human rights, being moral.

"Everithing is political" means that nothing can be fully separated and insulated from the surrounding political atmosphere. I personally think it is not a constructive way to perceive the world, but it is perfectly self-consistent