Your theory has merit. If you step back and look at the strategic importance Britain placed on the Bismarck threat, it seems they really were fearful of the damage the ship could do to convoys.
Note how just about every available ship has been thrown into the effort to stop Bismarck's mission. While Crete was a loss to British prestige, the Atlantic convoy's represented much greater strategic importance to Britain's survival.
With good reason. That finally sank in for me a while back when I re-read the chapter in Wouk's The Winds of war that covers this period. The main characters are discussing the matter on May 26. Captain Henry says, ". . . unless the Bismarck is undamaged. In which case heaven keep any convoys she runs across. With that fire control she displayed, she'll pick off forty ships in half an hour."
For the first time I thought about the impications of that line. It means Bismarck could wipe out an entire convoy just like that. Britain couldn't afford to lose a whole convoy. Once would be a catastrophe. A second might have had them sending feelers to Berlin. That is what is at stake in the battle now beginning.