That's not how a HF supported by consensus works. What happens if the miners use hashpower as coercion as the network is that their blocks get invalidated and the coins that are being mined are worthless. The miners do not hold any 'superior' power over the network, else Bitcoin could relatively easily be manipulated (which we know is not the case). Anyone who thinks that people and businesses can upgrade their infrastructure within a very short time period clearly have no idea what they're talking about.

No. Firstly, nothing is happening. Secondly, it won't affect the halving either way unless you're concerned about the price (which is trivial).

The metric is very useless and especially in short time periods. We've observed this with exponential rises in both XT and Classic nodes, which disappeared very quickly afterwards.