Arthur Robson wrote this on Facebook:

If am peacefully working out, and someone else arrives in the gym, they usually grab the TV remote to bathe in the inane chatter of preternaturally perky news shows. What if I were to arrive while they were watching TV and switched it off?

Which is a good point but still I think that a case can be made that it is morally allowed to turn on the TV but not to turn it off.

If you walk into the gym and the TV is on, that fact is a strong signal that somebody is watching it and would be harmed if you turned it off.  On the other hand when the TV is off you have much less information about what people are paying attention to.  You only know that nobody turned the TV on.  This is consistent with everybody being indifferent to the TV being on and off.

The point being that a utilitarian calculation based only on the signal of whether the TV is on or off will always make it strictly more permissible to turn the TV on than to turn it off.

But note that the inference is a function of the moral code. And if people are following the turn-on-but-not-off code then the TV will be on even if nobody is watching it.

So what we need is an equilibrium code:  a code that works even in equilbirium when it is expected to be followed by others.