Totally understand where you're coming from, we the same concern at the beginning. We read through a bunch of TOSs and found that some prohibit the bars from modifying the stream, but they're allowed to change the channel / input whenever they want. We specifically designed our hardware to comply with this by changing the input on the TV instead of modifying the cable stream.
What prevents the TOS from changing to prohibit any automated attempt to circumvent the display of ads? The providers would have a huge incentive to do this if you become successful.
It may be a loophole, but I have a hard time seeing how it could be closed. Telling users they can't change the channel or turn off their TV when an ad is playing will never fly.
if it's switching the input source, I think that's a more grey area. It's legal for them to change the channel? I'm interested to see what comes of this