There's probably a bit of hard-headed [operations research](https://en.wikipedia.org/wiki/Operations_research ) going on.

To wit:

- in the big scheme of things merchant marine losses were manageable.  [Safety in Numbers – Calculating Probabilities for Convoys - Statistics.com](https://www.statistics.com/safety-in-numbers-calculating-probabilities-for-convoys)

> In the mid-Atlantic region, **convoys lost only 4% of their tonnage**, compared to 20% by independent ships.   

So you are passing ships through at 96% of their theoretical efficiency (note:  this is overall casualty rates, 1942 loss rates *were* higher but still relatively low outside of mass casualty events for specific unlucky convoys)

- your proposed route is, at a guess, *at least 50% longer*, in even worse weather areas, quite possibly reducing air cover effectiveness as noted by the other answer.  So your efficiency would drop to 66-75% and that's assuming no losses whatsoever.  Allied air assets being nowhere as efficient vs U-boats at the start, without advanced radars, as later on, when the gap was *also* being closed anyway. 

It sounds awful, and I don't mean to belittle the grievous losses by merchant sailors in [WW2][1].  

> There were 243,000 mariners that served in the war. And 9,521 perished while serving—a higher proportion of those killed than any other branch of the US military. Roughly four percent of those who served were killed, a higher casualty rate than that of any of the American military services during World War II.

But during an existential war your idea would not receive much consideration, IMHO.  Those were acceptable and manageable losses, while throttling the efficiency of your merchant fleet overall would not have been.


  [1]: https://www.nationalww2museum.org/war/articles/merchant-marine-world-war-ii