It's not? Hmm, well, let's do some math.
The Bureau of Labor Statistics says that in 2010, there were 113,700 architect jobs in the US, 79,000 civil engineering technicians, and 262,800 civil engineers.
That's a total of 455,500 workers in what are probably the most directly relevant fields, which means this list of 1700 represents 0.37% of those workers.
Now you mentioned that this was nothing like evolution vs creationism. I disagree, because the Discovery Institute (a creationist group) has a list signed by ~760 scientists claiming to be "skeptical" of evolution. 760 is not as much as 1700, but in the scheme of all the people in the relevant fields, they're both pretty small numbers that are more or less irrelevant.
Of course more importantly, they don't have evidence to support their position, so how many of them that there are doesn't really mater anyway.