WCW, ECW and ROH have never shied from defending the TV Title on PPV/iPPV. You watch PPV's on your TV (except in the case of ROH), therefore it is fitting to be defended on PPV as well as TV.
If they went with the fact that not everyone can watch a PPV, then why defend any title on PPV as normally fewer than 10k see the PPV's while a million watch the TV show. Putting that title on PPV means more reason to purchase if they can make that strap more prestigious. Also if it is only defended bi-monthly you are going to have fresher matches over that strap on both TV and PPV, which is more reason to tune in (or not switch the channel) or buy the PPV, you won't be getting stuff like Robbie vs Devon 38 times in a 6 week span.
How about this idea, have him defend the title once every month or 2, but have non title matches every week or 2? A tv champ should wrestle on Impact a lot even if it's a non title match.
Plus non title matches are a great way to build up for a title match. For example you see someone beat the champ in a non title match but loses during the title match.
What do you think of having the title only change hands at a ppv, but everything else on Impact? I don't like that idea but some might.