Because the US can replace navy, Germany really can;t replace FIGs.
That US fleet is going to down 1 FIG, and pretty fair odds of 2. US has already built 2 more TRNs, and has moved their Panama DST to SZ10 so they can repeat that move in US2. Germany meanwhile has comitted 4 FIGs to kill those ships… 4 FIGs that cannot be sued to counter in Norway, nor be used against Russia in Ukraine or West Russia, or against UK in Egypt.
Basically, it is a sucker move.
You get Germany to commit and LOSE forces for no real gain, and draw Germany;s offesnvie pwoer away from battles where it could ahve a serious impact like Ukraine, Egypt, and Norway.
And Norway is minus $3 to Germany and +$3 to UK, making up for the loss of India, and weakening Germany.
So long as I can consistently weaken my opponent and still be able to maintain pressure, I will often sacrifice units to that end :-)
And I thought I did specify that the US sent 1 FIG and 1 BOM to UK…