...if people who have become quite proficient in Aikido would view a second MA as an augmentation of their skills by adding more "weapons" to their arsenal or a hinderance by learning new skills that may not fit well with aikido...
I would have addressed your question sooner but I am not highly ranked in Aikido, perhaps partially because I spend much of my time doing other things.
Certainly, more correct practice will result in more skill. Whether any of these skills "fit" with Aikido is, to me, unimportant. If I practiced Aikido as a religion I might feel differently.