Well, I share your concern for NASA, but for very different reasons. However, in the interests of brevity, I will stick to the issues presented in your article.
First, interest in a device which may be entirely impossible doesn't mean someone is being unscientific - quite the contrary - if the laws of physics are going to be repealed, a full and in-depth investigation is certainly called for. If I show an interest in chemistry, does that make me a chemist? If I show an interest in violent TV shows, does that make me violent? No, of course not. Don't read into this any farther than what it is - NASA is curious. It has a responsibility to seperate fact from fiction, and if this "reactionless" drive isn't on firm scientific foundations, they'll debunk it and move on. I would be more concerned about them spending serious money on it, or making public announcements that it is feasible - none of which I have seen, and none of which is mentioned in your article.
The essence of science is skepticism and questioning. Einstein himself said he would be dissapointed if nobody ever proved him wrong, because then there would be no progress. A NASA scientist deeply questioning general relativity is good - it shows he is thinking. In Geometry, I take nothing at face value until I see the proof, and likewise this scientist was likely just asking "Well, why is that true?" There's no harm in that, and it's hardly unscientific. He could have just as soon been discussing why there is no conclusive evidence that crystals have psychic powers. If you must judge, judge on their published works and experiments.
The questioning of NASA's scientific reasoning aside, let's examine why they might lie or exaggerate claims. Like anyone else, they are human. Their budget depends on keeping the public eye and they know it - so if that means occasionally releasing a report speculating on life on Mars, if it keeps people's attention, so much the better, I suppose.
However, by the same token, many people assume that things which are controversial are correct. Take EM radiation for example. There's alot of talk about cell phones causing cancer and whatnot. Well, truth be told, there is very little in the way of proof that EM radiation itself can cause any adverse affects on someone's health. The principal danger in high energy EM radiation sources is in the AC voltages carried on the line. There's not much dispute about what'll happen if you happen to touch one and form a path to ground. That isn't to say there isn't a risk. It hasn't been conclusively proven that no risk exists. It may be entirely possible that the radiation is highly dangerous, it's simply unlikely.
I'm going to go out on a limb here and say that there are other, perhaps more important, things to be questioning besides NASA right now. If you have to question anything about them, question their leadership and the management that would allow something like the Challenger disaster. Question your elected officials for not persuing the final frontier, arguably our future as a country, and maybe for the entire species.
Now for some pure speculation... NASA's total budget for fiscal 2000 is less than what it would cost to build a couple stealth bombers. With overpopulation and the current expenditure of our natural resources, if we don't change something soon, we'll bring about our own destruction. Space may very well wind up saving the global economy as resources dwindle and prices skyrocket. We gotta get off this rock.
Society needs therapy. It's having
trouble accepting itself.