Oh, this webcomic doesn't actually use the word "xenomorph" (that I know of), and in fact I don't think many people would, but I have come to consider it a very nifty term. Kaiju or dai kaiju or giant monsters are other, more common terms. I first saw the word xenomorph used in signage in a Godzilla movie from the 2000s, (I think it was Tokyo S.O.S.) and liked it. A bit of Googling revealed the term is perhaps better known as the creatures in Alien, but I think it's usage would be broader than that, simply meaning a "monster". As evidenced by this. In fact, "xenomorph" isn't even in Dictionary.com, although "xenomorphic" is, meaning simply "strange form" although applied to minerology rather than biology. I would think it could mean "foreign shape" or "alien form" as well. Now that I think about it, I suppose macroxenomorph might be more accurate for Godzilla and ilk, while a xenomorph is probably human-to-elephant sized (think, Tremors). A microxenomorph might be a parasite or "bug" of some sort.
The webcomic is Kill All Monsters and I found about it on another blog, herein posted. I was worth looking at, and the artwork is well done. The story to me seems a bit ungrounded in reality, but when you are making a fun-loving melee comic about giant monsters roaming the Earth, I suppose being grounded isn't exactly as important as artistic licence. I suppose I'm just more of a Hard SF guy myself. Even before I realized there was such a distinction in the genre.
I have to give major props to whoever it was who thought to give their giant beetle xenomorph an inner skelaton as well as an exoskeleton, revealed during its beheading. Anyone who knows about such things realizes that giant arthropods, if exact replicas of current species, are...improbable.
The whole Eiffel Tower thing was disqueiting. Intentionally destroying a monument to human culture has to be a crime against humanity in somebody's book. Perhaps is was merely a reconstruction and thus not especially valuable?