The point is that 与えられる can be both the passive form and potential form. In a very specific context where 与えられる can be potential, と also can be grammatical other than に. と after 荒谷 should be や even for that case, though.
見れば間違いなく荒谷やその手下A、Bの嘲笑とさらなる屈辱を与えられるからだ。
If I see it, I can no doubt give "荒谷やその手下A、Bの嘲笑" and "さらなる屈辱" to someone/something.
The recipient of 嘲笑 and 屈辱, which is marked by に, is omitted here since it's obvious from the context.
To tell the truth, I, too, thought 与えられる was potential at first. I think this is a good example how important the context is to interpret the meaning correctly (the readers wouldn't misunderstand the meaning like me since they already know the flow of the story so far), and the trivial thing like と after 荒谷 can be a critical key, like bentenmusume-san would realize it consciously or unconsciously.