10m would have been at least another 30dB to 40dB of attentuation depending on the efficiency of the transmit antenna and the receive "antenna"
Agreed; whilst it all makes for a good anecdote it still sounds a bit suspect. Firstly a dummy load is not intended to radiate (OK; they always do even if it's only very slightly) so the normal aerial should not have been in circuit. If, however, it was an attenuator then having the aerial connected and functional would make perfect sense.
As stated by "horsham_sparky" there would be substantial path loss between aerial and "target" so the ignition of the flash bulbs as described sounds highly "dubious".
Enquiring minds would like to know, and all that...