The textbook the publicly funded school is endorsing is "Of Pandas and People" and there exists testimony from prior litigation that the author of that particular book used "creationism" and "intelligent design" interchangeably. In the testimony, the author asserts only agency as intelligent cause.
Reading between the lines here (since I haven't read the book), that means the author did not present phenomenon along with agent as alternative types of intelligent cause. Without that, the court is most likely (IMHO) to consider the endorsement of the textbook as prohibited under prior Supreme Court decisions vis-a-vis the Establishment clause, especially Lemon in not serving a secular purpose.
Looking at it from the Supreme Court level (should it be appealed) - there is a possibility that Dover would prevail since the Supremes need to clarify their own conflicting decisions on the First Amendment. The consensus of the court is that Lemon causes confusion.
The decision in the 7th Kaufman v McCaughtry finds that atheism is a religion (see especially page 8) - based on previous Supreme Court rulings including Lemon.
Should this Dover case be appealed (and/or Kaufman) - then the Supremes will be faced with defining when atheism is religion and thus whether refusing the referral to a textbook such as this one would constitute the endorsement of atheism as the state religion.
IOW, the court will need to clarify what it meant by secular purpose if it keeps Lemon or establish a new test for "what is religion" and what actions constitute the establishment of one v. what actions would prevent the free exercise of one.
Whew, that was a mouthful before 7:30.
Thanks for outlining the actual case stuff, the media is so lame about that!
DK