C'mon Megan, flying a multi-ton airliner 5 miles behind another is hardly similar to a man-sized jetpack metres from the wingtip..
Capn Bloggs, my post
I think that the three months they took in planning and briefing this exercise (by professionals) were fully aware of the risks and what was needed to ameliorate those risks.
In making my post, and in particular referring to the professionals involved, I would have thought that everyone would have been aware of Yves Rossy, and his background as ex fighter pilot, airline captain and developer of the strap on jet powered wing. It's not as if he has not had notable media presence prior. With his background would he be aware of aircraft wake, vortices, and what they might do? Probably yes.
"unnecessarily reckless"? Absolutely not. No different than the formation carried out by aircraft large and small in the worlds armed forces. The only difference is the capabilities of the respective aircraft and the limits applied, and their three month preparation would have covered all that, as I said in my post repeated above, "
were fully aware of the risks and what was needed to ameliorate those risks".
This Blue Angels Diamond Formation Is Terrifyingly Tight
That's not to say even the experts don't get it wrong