Which TOS are you referring to? The Android Marketplace TOS? Could you please point to the section of the TOS that mentions this? I find it very strange that the marketplace would be concerned about an application's bandwidth usage.
(f) is deemed by Google to have a virus or is deemed to be malware, spyware or have an adverse impact on Google's or an Authorized Carrier's network;
Using the network's bandwidth to tether (since you didn't pay extra for it or is not authorized to) is deemed as having an adverse impact on the carrier's network.
