As far as I know it makes sense because, actually, in a land war (as WW1) artillery is typically kept covered (defiladed) and only goes on the
posizione di tiro, the "fire field"(?), when it has to operate. The fire field is by geometry uncovered and so just like your artillery can hit the enemy, the enemy can hit your artillery.
Heavy artillery takes hours to move. It can never be too near to the enemy (it would fall in his hands in case of a sudden penetration) and it can never be, er, too far. And it must be "covered" from enemy attacks until use.
What I can gather is that, considering that a landing is typically performed in the morning, during the hours before the possible landing the artillery must leave the covered positions and go to positions favourable for shelling, possibly or probably uncovered position. This is risky.
What Rommel presumably did was to order his artillery to remain covered instead of going to the fire fields before the morning.
One of the reasons why the Solstice battle was won by Italy, against all bets, in June 1918 was that two Austrian deserters gave the time of the Austrian attack. The fire fields of the Austrian army were known to the Italian army (which had "air superiority").
So in the night hours before the attack, which obviously begins with a shelling, the Austrian heavy artillery moved to their fire fields. The Austrian attack was to happen on basically all the length of the front (they were so sure to pass that did not concentrate the forces to strike in one point). The Italian artillery moved before them and before the hour of the Austrian shelling shelled the Austrian positions while the Austrian artillery was positioning. That played havoc of the Austrian artillery and greatly diminished their push on that day.
The juice of this is that artillery, by definition, moves from covered to uncovered position, to go back to covered positions, and those movements belong to the logic itself of the heavy artillery use. These movements can span for kilometres and take hours if I get it right. Moving the heavy artillery to and from the fire field is a very delicate decision which can be liked to the decision by an air carrier to launch its planes (especially if it has no battleship for coverage).
What I wonder is what "covered" (defiladed) means if the menace is an air menace. A battery which is defiladed behind a mount is obviously not reachable by the enemy heavy artillery (because they cannot shoot with a mortar trajectory). A plane, on the contrary, can turn round a hill and attack a battery from every position in principle.
In practice bombardiers don't do complex manoeuvering and maybe the artillery in the rear was more protected by just being farther from the coast, I don't know. But I must have seen a documentary about this artillery mistake by Rommel, misguided by the whether. Or maybe age is taking its toll from my memory
I agree that in WWII and with an air menace all this movement of artillery does not sound very logic.
It might be that the feared attack would be carried with naval artillery.
