Yes, that is the problem with Aquinas’ argument against ordaining women. If, as Thomas says, women represent subjection, then they should be the preferred candidates for priests. They better represent Jesus who took the form of a slave, accepting even death, death on a cross! Accepting punishment for a capital offense is the ultimate subjugation. But Aquinas thinks Christ cannot represent subjugation because he interprets ordination by “ applying a hermeneutic of power.” That kind of argument just does not work, as you say.
It is also hard to see how the scripture argument works. “Scripture is the soul of theology” as St Jerome said. To say this issue is absent from scripture is a problem whether you want to say that absence excludes women, or that that absence means we can decide.