A whole lot of the "Architects for 911 truth" (or whatever they called themselves) were not architects, or had lower level degrees.
Note that the claim is not that 1700 lawyers have signed the petition - it is that 1700 Law Professors signed it.
This is different from the 9-11 Architects for Truth in two ways:
1: Getting a law degree and passing the bar (being a lawyer) is generally harder than getting the sorts of Bachelor's Degrees and other crap that many of the Architects for (non)Truth have.
2: Getting a professorship is even harder.
If 3000 Professors of Architecture called for an investigation into 9-11, I would take that seriously. That stupid 9-11 group was full of people with lower level degrees, or irrelevant degrees, or no degrees at all but they had played with legos. There were a handful of real professionals in the mix, but much of the people who signed on were not actual architects. We know that, there were hundreds of pages in this forum going over that.
Actual University or College professors are, for the most part, going to be functioning at a higher level than that. That said, I am sure of the people signing on are not actually qualified, or are "Professors" in name only or of backdoor/basement diploma mills. Still, just limiting it to professors is going to make for a much more selective list than that 9-11 crank group.