That’s my understanding as well. He’s saying basically “it’s not what you think” in a slightly embarrassed way probably because it’s at least partly true, but he doesn’t want to appear so callous.
p108
Note that in the dictionary entries only the 2nd one is marked as being “suru verb”, so I think it’s the one to favour here.
I think I would translate it as “Because even non-wizards can use it, it is prized/commonly used all over the world but [because only wizards can create it, it’s expensive]”
That’s actually quite usual! ため can mean both ‘because’ and ‘in order to’ which is kind of weird for the English-speaking mind, but works for them ¯_(ツ)_/¯
The Dictionary of Beginner Japanese Grammar (strongly recommend!) has a lot to say about ため, and one aspect of it’s use here is that it’s more formal than ので or から.
Subjectively from my reading, when used in this sense I feel like ため allows room for other reasons where ので or から feel more direct/causative, but I don’t know if that’s the case and maybe the softer feeling I have with ため is just due to the politeness register when it’s used. But polite Japanese is often less direct / more vague / open to another perspective, so maybe my feeling there is at least partly true.
DoJG also comments on how to distinguish these senses if you’re interested, and it was an interesting read. I feel like context normally does the job, though.