Of course, this way is quite dangerous, and violates radio frequency regulations, but if it's a war, who cares.
Plus there are multiple channels at 2.4Ghz, and you are probably outputting a narrow single freq.
But that's just me guessing, I'd love to know if it would actually work.
I too would really like to know, and try it too, but getting permission for 800W transmission would be a pain.
Good 802.11 radios can do 1000mW.
A microwave oven magnetron and a simple aluminum waveguide is many hundreds or thousands of times more effective radiated power.
For what it's worth, this attack can be sidestepped fairly easily just by not using open frequencies, to which microwave ovens are usually tuned(for regulatory reasons). This is only useful against drones that are available to buy for individuals, as they are forced to use the same open frequencies. Anything military grade is likely using other frequencies, and you can't use cheap microwave ovens to generate ridiculous amounts of them.