I disagree, see:
The one who broke Linlin's bones and forced her to use her soul power to heal herself was Law not Kidd.
The one who Linlin complimented by saying their techniques were "pretty dangerous" was Law not Kidd.
All Kidd has done (prior to Electromagnetic Cannon at least) was pushing Linlin around and smacking her with metal. He was dealing mostly superficial damage. The person really fucking her up has consistently been Law.
Law is not only a much better matchup than Kidd against almost every character, his offensive prowess is consistently outright superior.
I could place them in the same tier list, but Law would rank higher for me.