If I'm understanding it correctly then the answer is not much more than our present system. You get low power consumption in your device by being parasitic on a high-power monochromatic antenna furnished by the local WiFi.

There might be interesting attacks with other high-power antennas in the region creating pockets of destructive interference -- essentially localized denial-of-service type stuff.

The other risk you're taking is something like "the operator of this antenna can induce bit flips and such in your communications," which is true, but they wouldn't know what bits they're meddling with because they have to commit to the inconsistent signal before you use it. But they can already send arbitrary local packets pretending to be you at that granularity. Certainly if we're talking about the signal source managed by the WiFi operator, there is no dispute that this doesn't empower them -- they own the router, where they already have direct control over your internet communication and what they "hear from" and "say to" you.

Compared to the threat of opening your own access points with a suggestive name and just letting people connect to you, which you can also do with this range, being able to meddle with packets in a haphazard way doesn't seem very scary.