Kakashi doesn't know enough about those goings-on to know much about that side of Ulq. But he doesn't much care for Ulq.'s assessment of "weak" for either an emotional attachment to one's teammates or for Obito himself since Kakashi, in his younger days, would have made that very same statement about Obito or caring for teammates...and because it was Obito's death that changed all that.

Way to unwittingly guilt-trip him! XDD <3