I've seen this very same topic here many times before and I usually ignore it because (to me), like now it's getting too over-blown. The tech at Bay13 (Rich)is another Volvo dealer master tech like myself and we see this problem very often. The wiper arm/trans linkage "system" is so simple that it could have existed 100 yrs ago, hardly high-tech stuff here.
People can and often do also try bending the upper arm section and or blades but that's usually why they then hit the hood. I've seen where people do that too.

The problem I see is that the lower part of the left arm gets bent out (something physically causes that, like heavy snow or frozen in ice, etc) and assuming that the upper part of the arm (thinner part) and blade is also not bent too, the lower part can easily be re-bent succesfully and once done correctly, it won't just go back to its "bent position" all by itself from normal use. There is no stress or other reason why it could just re-bend by itself from normal use in warmer weather (no snow, ice, etc).

Bending the lower section will also not damage the wiper arm trans attachment point (where the arm attaches with the 13mm nut). That part can't easily be bent by any means.

I know, there are those Volvo purists around who can't imagine "tweaking" anything as if to them, that'd be "butchery" but if that's how one really feels, go buy new wiper arm parts and spend some money. The new parts will definately have correct geometery right out of the parts bag.