Earlier quoted context omitted.
The linked article refers to three ways bittorrent can deanonymise you behind Tor. That's a privacy concern, not a load problem.
Yeah, but you can deal with that, if you know what you're doing. If you use Whonix, or roll your own Tor gateway, leaks around Tor aren't an issue. UDP is the hardest thing to deal with. I mean, with proper Tor/userland isolation, leaks don't happen. So all UDP just gets dropped. If you want UDP, you need to use OnionCat or tunnel a VPN through Tor.
I think it's fairly clear at this point that ZeroNet isn't testing to make sure that this is the case.
Their TorManager [0] is basically a wrapper around the tor executable, and runs a fairly vanilla config.
So yes, leaks or attacks via bittorrent are actually an issue here.
[0] https://github.com/HelloZeroNet/ZeroNet/blob/master/src/Tor/...