Sticking with the theme of definitions, I would say that depends on what your definition of "exaggerates" is
They are facilitating his demonstration. There is absolutely nothing wrong with that, but it must be recognized for what it is.
So depending on exactly what you choose to believe is being demonstrated, you may well find that it is being exaggerated.
Just curious as to what part of Uke's performance you think the Ukes are exaggerating - the vocal grunt or the range of their movements?