What more do you want them to do?
Although the service seems shady, if everyone did this wouldn't it be for the better? (albeit at cost of slower connections)
Decoupling IP from people won't happen anytime soon. It's better for law enforcement to just go, seize everything, and deal with the false positives later.
See the long list of "suggestions" for people interested in running their own tor exit node [1]. This is not something you should even think about doing from your personal home, mixed with your own traffic. It's asking for trouble.
[1] https://blog.torproject.org/blog/tips-running-exit-node-mini...
This, come to think of it, sounds like a more ideal approach to creating exit nodes (whether for Tor, a more traditional VPN, etc.). Some low-profile innocuous-looking wall wart - perhaps with USB ports to double as a USB charging station, or some other "clever" disguise - could really be an "exit-node-in-a-box", relaying Tor users through public wifi hotspots in restaurants, hospitals, etc. I reckon this will be more prevalent if any jurisdictions start doing silly things like holding people liable for what their computers emit when they run exit nodes (or - worse - ban Tor, VPNs, etc. outright).
The issue is there's no informed consent. Outside of /r/netsec, /r/techsupport and HN etc, there probably aren't people who know how Hola works and what the implications are.
You can bet the majority of Hola users don't know what a MITM attack is. I'd wager more than half wouldn't know what a bot net is, or what an exit node is.
Most Hola users have not given informed consent.
Hell, I'd wager that more than 90% of their users have no idea what a bot net is.
Most people use Hola to watch internet shows not available in their country. Or, for example, some people use Hola to watch southparkstudios from Sweden, because it's freely available there, but in the US it requires hulu plus.
I'm on a college campus, I am always peeking at people's screens in the library and I'll see the little Hola flame in their navbar. I even saw it on a CS grad student's browser once before class.
No one has any idea.
So far as I have been able to discover, the number of times your scenario has occurred in real life could be counted on one hand.