Shouldn't the engines be more of a concern than the windows?
"The 4kg “projectile” (the term is the one used by the study’s authors) was made up of a number of loosely drone-related components, including arms from quadcopters – and, strangely, a full-sized SLR camera, something not found on commercially available camera drones"
Oh? Not found?
"DJI Spreading Wings S1000+
Your DSLR in Flight"
Just because they don't bundle the DSLR doesn't mean there aren't drones on the market that are made to carry a DSLR.
I'm not sure what your issue is with this test. It's a perfectly reasonable approximation of a high-speed collision with a large drone. If a large DSLR-carrying drone enters a jet engine it is rapidly going to become a loose assortment of parts, each of which may have the potential to cause damage.
An airliner was taken out of service for 5 hours for inspection when an old lady threw *coins* into the engine. I'm pretty sure coins weigh less than 250g.