Hmm, that's a somewhat lenient example there (T1 Rules and Guidelines) and the other doesn't really cover preps. I would argue prepping falls under the same realm of fighting being heavily frowned upon in introductions, because it gives whoever posts second a major advantage by being able to initiate the combat with the element of surprise -and- giving them a leg up on preparing attacks.

It's up to individual interpretation, but usually I would reserve introductions for story and descriptions, and launch into any prepping or fighting in the following round.