I checked the rules for both the new and the 2001 versions, as well as the rules and a strategy guide for XXXenophile.
None of them said anything about the orientation of the replacement cards. They do keep mentioning how it's a good idea to leave your opponent with bad moves, but don't mention if you can use the orientation in addition to the card choice to do so.
How ever, I would argue that you are allowed choose the orientation of the replacement cards for two reasons:
- Nothing in the rules says that you'd need to honor the original orientation.
- Especially when popping multiple cards, keeping a track of the original orientations can get tricky. I find that game designers tend to avoid requiring players to remember hard-to-track information, which would make keeping track of all the orientations "poor design".
I'd say you freely choose how to play the cards from here on out. It does effectively double your choises on each replacement.