To far more Americans than you apparently imagine, "nebulous fear" is not applicable with respect to Muslim entities involved at U.S. port facilities.
Simply put, Islamic countries (included our "new friend," the UAE) have historically not yet warranted the type of trust required in so suseptible a crucial hub of commercial and trade distribution centers as ports.
The risk factor may be "low," but not comfortably low enough.
No, I understand that. It is an honest assessment of the opponent position. But it would be wrong to confuse honest but mistaken fear for a real threat.
On Sunday night's West Wing, they actually allowed Alan Alda's character to come out and defend nuclear energy again (I thought they wouldn't, because he did so well in his "live debate" that I thought the environmentalists forced them to write a nuclear meltdown into the show to stop the bleeding).
He pointed out that you were much safer living by a nuclear power plant, than you were driving your car. But people are still truly afraid of nuclear energy, because of what WE know are lies, prejudice, and ignorance.
I would say that many opponents of the terminal deal were truly afraid, for the same reasons -- lies, prejudice, and ignorance.