Because of the damage it does to real science
Whatever one believes relative to the very start of life, as we think of it, I don’t see how ID damages science at all. If anything, science has been damaging itself for some time, because like senators who fail to husband the powers of the states they should be protecting, scientists have too often forsaken scientific methodology for the more popular, more lucrative paths of fame and money.
If science, as related to this subject, is so overwhelming, ID cannot possibly be a threat. All that’s required is for “science” to answer the question of how we first got here. And it evidently cannot in uncertain terms. If that is the case, the question is still open to thought, argument, study, and serious speculation. That’s the scientific way.
It really isn't a threat. It's a tiny fart in a very big hurricane. The principle is dangerouse however.
I didn’t know you were here (or maybe I did and forgot). You’ve been here longer than I have. :)