An Incapsula competitor, ScrapFly, explains why they think the
blocking is primarily Javascript based:
https://scrapfly.io/blog/how-to-avoid-web-scraping-blocking-javascript/
"..javascript is by far the most powerful tool because it allows
arbitrary code execution on the client machine."
The work of the Devil.
I had the site not work in FF with No-Script nor in Opera with no
restrictions. But we are not getting to the web page at all, so
JavaScript is not involved. It's a filtering proxy, and We Are Not
Welcome. Not, as far as I can see, that anyone outside the US has any
use for the site.