Based on your description of how / where the tire lever went through the rim, the rim is not necessarily stronger in that area. The further from the bead you get, the less “structural” the rim becomes (even a few mm can make a difference).
Many tire levers are reinforced with steel, significantly increasing their strength / durability. And even the straight plastic ones can have very hard lips / tips. And honestly, from someone who used to do product development in the bike biz and still works in consumer goods, there is no way for them to know if you did actually use a plastic lever. For all they know, you used a steel lever, poked through the carbon and are now saying you only used a plastic one.
I know it sucks, and I feel your pain, but the hard reality is that this simply isn’t a warranty issue.