Doesn't look like insect damage to me. More like two tomatoes fused together or some kind of anomoly like cat facing. Nothing to be concerned about, in my opinion.

Lots of things can cause holes and are seldom a cause for concern. The "perfect" tomato is rare. :-)

Dave

Let it get ripe, if it stills bothers you, just cut around it and eat the rest. Growing indoors, it would be very unlikely to be a worm. The picture is not closeup enough to really see if it is a fresh cut or an natural dry open growth thing.