If he's playing with the worse wingers that the Kings have to offer, he's not going to get good strong defenders there either. Besides, this year his wingers have been a motley mix of Vesey, Engvall, Mikheyev, Thornton, Simmonds, and Spezza. Those guys are all decent NHL players, but Spezza is the only one who actually generates notable offense. And the Leafs are a defensively responsible team. Perhaps not quite to the degree that LA is, but Kerfoot has no problem playing defense. He's not particularly noteworthy at it, but he's not a floater who blows the zone early.
I don't mind hearing fans say their teams don't want him. There's nothing particularly exciting about him, nobody is going to get hyped to have Kerfoot join their team. But arguments like, "he's a cap dump" and, "he'd score less here" just don't make any sense. He's a NHL 3c playing a vanilla NHL 3c role with typical NHL third liners. Put him on any team in the league and ask him to play 3c with some typical 3rd liners and he'll do roughly the same thing. 35ish points while being average defensively and decent on the PK or PP. At 3.5m per season, that's about what you expect: a 3c who can do the job well enough.