The AGPL does not prevent Amazon from linking their proprietary code with mold. It prevents you from selling a linker service that is built on mold without giving people the source code to mold.
My understanding of AGPL is that Amazon wouldn't even have to open source their service. So the license is not in the way of commercial exploitation.
In fact, OP makes exactly that point, that he is thinking about needing a more restrictive license, not a less restrictive one.