I think it’s nonsense. Conflation of aircraft enhancement of vhf signals with wsprnet records for HF signals.
IMO, an aircraft can’t impact HF signal levels that are dominated by ionospheric reflections, not to any measurable effect on a 115 second integration time. No meaning other than ionospheric changes can be reliably derived from variations in reported signal strength from one period to the next.
Leaving aside the lack of the necessary VHF transmitting and receiving WSPR stations on either side of an unknown flight path that was probably into the Indian ocean where VHF enthusiasts are a bit thin on the ground.
Andrew VK1DA/VK2UH