It’s quite suitable for specific RF situations provided you have done the right characterization work.
https://spectrum.ieee.org/with-the-dead-bug-method-hobbyists...
https://hackaday.com/2016/05/04/getting-ugly-dead-bugs-and-g...
1) First and foremost, the board or box the components are soldered to forms a very good ground plane
2) The parts are organized so that the circuits fit the enclosure
3) The part leads are used to provide relatively rigid support for the parts
4) Where they can't, it looks like the builder used epoxy
You could argue that the builder should have cleaned off the solder flux and you'd probably be wrong, because you probably don't know what a pain it is to really clean off solder flux to the standards of high reliability circuits.
Folks that are used to breadboards and perfboard construction have a hard time appreciating the care that goes into good dead-bug assembly. That is probably a fairly high performance circuit and is probably much more rugged than the typical perfboard sewing card.
How ironic, given the website also does not support HTTPS.