This Norway move takes way too long to execute and doesn’t do much to cripple Germany. Under the best conditions, its US 4 at Gibraltar and US 5 at SZ112 to Norway, which is often a very dangerous place for you to put your fleet as the Allies. You could potentially be crossing to SZ 119, but that costs you a SeaBase and you are still only gaining the SZ 125 position.
The sad fact is that by the time you take this 8IPCs away from Germany, he has already got 60-70 income. You don’t really diminish his forces this way, as in most games the pieces that Germany had in Scandinavia have joined on the attack with Russia. Ideally, it is Russia that takes Finland and Norway rather than the Western Allies since that gives them a NO of +3, but of course that would require diverting critical troops.
It does potentially create a backdoor to revive Russia, but a relief fleet can reach Novogrod as well, which is a much more strategic position to be in with both your fleet and your land.
It is not really any more appealing for the Western Allies to attack the Atlantic Wall or the Mediterranean either, so attacking Norway may be a “best of worst” option since it is much harder for Germany to defend and could potentially diminish their income at a time when they need to build in many directions. But because they will be right at the door to Moscow at this point, you may not have your UK support fighters to count on, and in any event, it doesn’t seem like the Allies are capable of taking a well defended Norway AND attacking some other useful objective at the same time.
If that were the case (that you could take Norway with a small, sacrificial fleet and not be subject to any german counteroffensives) then do it. But it won’t usually play out like that and in order to safely build the MiC there you will have to bring all the US and probably all the UK pieces up there to do it.