Giving youngsters a game is fine. Targeting opposition that haven't yet won in the league for introducing youngsters is fine. Choosing a side made up of first-team squad members is also fine, and shouldn't incur any penalty from the RFL.
If not forced into it by injury, then leaving out two of your three most potent playmakers (Leuluai, Sam), the captain and on-field core of the defensive line (O'Loughlin), your trusted pressure place-kicker (Pat), all at the same time to introduce those youngsters is always risky, and was clearly a misjudgement today.
Really, the upshot of that game is that it's two 'safe' points lost, and a bitter lesson regarding team selection. I'd be amazed if SW makes the same mistake again. Those two points may not matter come the end of the season, but I reckon everyone would rather have them than not.