AA does a similar thing on many of their flights. I couldn't even convince them not to load any meal for me. My goal was to bring my own food so that they wouldn't load a meat meal for me.

One reason some people are Veg is to stop animal suffering. If AS/AA kills the animal anyway yet you don't eat it, that doesn't stop the suffering.

If AA/AS won't offer a special meal they should at least offer the ability to have no meal at all.

Meat on the side isn't sufficient. It doesn't stop the actual issue.