Yes, weird choice. I understand @ratique explanation, but to me, it makes way more sense to have selection on the left: first you select, then you read. Tapas comics are read from left to right.
There are already the arrows to change pages that are weirdly (and terribly annoyingly) placed on the wrong side (in this case, left) on the current design.
I wonder if someone in Tapas is not at all sensitive to this kind of ergonomical considerations? It's pretty distracting...
For the comments though, right side looks good to me; you read, then comment. I, however, understand it may be a bit problematic in the sense that it blocks the vision (it's nice to have the right side 'open'), but I suppose they disappear at will (not sure).