When it comes to toilet dynamics it's not that big of a deal. Especially as a guy sometimes my aim isn't that great and I guarantee that causes more splash damage than any flushed toilet does.
Sitting down to pee in prison makes sense for that reason, but unless you have a shitty toilet/don't use a lot of water there's minimal splash and in Japan you have the magic water missile it shoots up your ass to clean it.
Think about it. If toilet splash was a big deal, they'd have outlawed urinals a long ass time ago. The rock girl is normal.