I confirm that when under a dome populated by red coral you should stay face up, keeping your fins as low as possible and far away from the coral.
If the cavern is high enough you can stay vertical, when the space is limited you stay with your back down and your bell up.
Hitting the bottom with your fins (or with a back mounted cylinder) is of no concern there, as it is solid rock without silt or mud.
If instead you hit the ceiling, destroying the coral, as it can easily happen with the American style for cave diving, this is really a big problem.
Inside marine protected areas environmental protection comes before confort and safety of visitors.
Who does not agree with such a priority should not dive there.
Diving is allowed only following a local guide. And following means obeying to his/her instructions.
If the guide see a diver in the typical horizontal cave position, with flexed knees and frog kicking, the guide will not allow to enter the cavern.
Regarding kicking style, a special kicking technique has been developed for these delicate marine environments, called the horizontal scissor kick, where knees are always kept fully extended and fins never go above or below the body, so it can be safely employed either facing down or up.
But kicking techniques is off topic here, and I have already described this kicking technique in some other topics.
However my point is general. In every different environment you can find different conditions, requiring to adapt your techniques, your equipment and your behaviour.
You must follow the rules in place in each site, or avoid diving there. Saying "at home I do it differently" is no excuse for violating the rules set for a given site, organization, resort or wathever...
