i would not do it this way for long term installation. Well more specifically, i would install a T in the kitchen line, an plumb in the new line. Dont use that line tap, they leak eventually
I fitted one about 10 years ago. It leaked the other day. What a pain in the ass. The screw bit was plastic and it failed. The actual tap that mounts the pipe is fine.
The lad is selling the tap kit more than doing a proper job. T pipe is the most secure way to go. They never explained to turn off the mains before doing any work!