Could عالمين actually mean, since it is pluralized using masculine sound plural "just inhabitants of the world", not the usual translation 'the whole universe'? Otherwise, why is it used?
First of all this is rather a question on Arabic language as both عالَمُون or عالِمون are not used or present (in this form) in the Qur'an at all. As they sound somewhat wrong, at least they are not much used instead of the other options (especially in the first case)!
According to al-maany عالَمُون is one plural form of عالَم: which means world, creation and some even add any thing in the universe.
while عالِمون is one plural form of عالِم: scientist, scholar etc.