Radio waves travel for long.
I remember getting local AM radio tunes 100 km away from the border of my province where in theory the radio is being set for.
Broadcast AM radio stations here use hundreds of kW of output power.
This is a bit bashed GPIO pin on a 3.3V microcontroller that has a max current rating of 12mA per pin. Even if that piece of wire used as an antenna here were capable of loading the pin up to its max output, it'd be something around 0.004W - and in reality it'll likely be an order of magnitude or two lower than that. That's at least 8 orders of magnitude less power, and even allowing for the inverse square radiation power pattern, this this is only gonna be detectable at single digit meters in all likelihood.
This _is_ a bad idea, spectrum noise and interference wise, but it's unlikely to have enough power at either its intended transmit frequency any of its nasty harmonics to make it outside the rooms it's in. You probably might not want to take this to hospital with you, or on that camping trip near the radio telescope, but I wouldn't think twice about firing this up in my home workshop...
