Pickleball Rules Refresher: Imaginary lines?

I played with a partner the other day who would serve from just outside the "imaginary service side lines." He said he does it to maximize his ultra slice & spin serve. He also said that as long as he was behind the baseline he could serve from anywhere. Is that true?
According to the IFP rules it states:

4.D.    Service Foot Fault. During the serve, when the ball is struck, the server’s feet shall not:


4.D.1.Touch the area outside the imaginary extension of the sideline.
4.D.2.Touch the area outside the imaginary extension of the centerline.
4.D.3.Touch the court, including the baseline.