This isn't a debate about what view is correct but simply a question as to why ID should be taught over other theories that have been fighting longer
Not really. The point regarding seniority was merely to counter claims of pre-eminance of ID. However, you actually make this claim by equating ID with classic "design arguments", something with which the major proponents of ID would take issue.
Now hopefully you wil forgive my unfamiliarity with US educational and legal history (I'm only really interested in what is taught NOW), but the only court case of which I am aware is the Scopes Trial, under which Scopes was found guilty of teaching evolution. Was Nebraska Man ever mentioned? And what effect did it have?
Anyway, even if ID was being taught as the standard back in the early 1900s, it had almost certainly replaced the teaching of Biblical creationism at some point. Why did that occur? What evidence led to Biblical creationism being rejected in favour of ID?
And let's not forget that the Scopes Trial was actually defending Biblical creationism, not ID, from evolution. ID, as its major proponents at the Discovery Institute testify, is simply an injection of a detectable intelligent agent into the wokrings of common descent. No douby if Scopes had been teaching ID, he would have been found similarly guilty.