I'm guessing in 99% of cases this information is either ignored or dumped into a database where a surveillance dragnet will lightly touch every record regularly looking for specific matches.
But in the remaining 1% it will be abused to skirt around someone's human rights.
And maybe they're hoping to catch some really dumb terrorists that write down the "Death to America" forum on that list.
I do find it interesting that the form is not compatible with anonymous posting like 4chan.
It's the biggest reason why I am a huge fan of the idea of mandatory prosecution. If we can't afford to prosecute all the crimes we have on the books perhaps we have too many crimes on the books