Scraping is typically against a the website's TOS. Unless they had some separate agreement I assume it is difficult/expensive to defend. I assume that's why all those other tools no longer exist. Their FAQ does seem to suggest that they've worked with other airlines to adjust their frequency of scraping. It would be surprising if any airline allowed any frequency of scraping, especially with a for-profit site. Airlines can just remove the option to see availability on the website and force everyone to waitlist.
Regardless, if these kinds of tools exist, it may make it harder for us to find PZ space. Right now, those of us that know how and actually put hours of our own time into finding PZ space are probably a small group and that gives us a bit of an advantage. If their site went viral, and anyone could find PZ space easily, it level's the playing field and probably means less for us on average.
PZ space seems to have gone down alot over the past year or so (based on my own observations. I use to be able to always find some thing and clear at booking. I've had to waitlist for the first time on several flights this year. Is that due to seats.aero? probably not, but maybe it could become a factor.