So instead of trying to pass Gibralter, which was extremely dangerous, the sub has to get across the Sea of Biscay, which is at least the second most dangerous place for an Axis submarine
As for Straits of Gibraltar, RM did pass through the straits with a 28 submarines without losing a single one, having enough subs in 1942 in the Atlantic coast for any operation. As for Bay of Biscay, in early 1942 the Bay of Biscay wasn't really an issue yet. Checking quickly from uboat.net, in 1942 the U-boat arm lost the following boats in Bay of Biscay: