My understanding of malware is that it must cause some problem for the user.
To sue them you'd have to show some actual, concrete harm. For example you contact a site that is blocking you and they tell you it's due to a certain request and you trace that request to the proxy.
> Plus, IP addresses rotate once a day
And I would be miserable if I were subjected to the volume of captchas and blocks on my regular internet connection that I see on the occasion I use Tor.