Why skip from one Shimon ben Gamliel to the next?

Question

The first chapter of maseches Avos goes through the mesorah from Moshe Rabbeinu through the zugos who are all mentioned by name with no gaps, culminating with Rabban Shimon Ben Gamliel and his grandson Shimon ben Gamliel.*

My question is, why not list the leader ( let's assume it was Gamliel of Yavneh) in between the two? I can't assume he had nothing to say. There was a fifty year span of time from the death of Shimon ben Gamliel 1 until the birth of Shimon ben Gamliel 2. This was the period of time referred to as the second and third generation of Tanaaim, why just leave it blank?

The next chapter begins with Shimon ben Gamliel's son Rabi Yehuda HaNassi so again, there is no gap there.

*This last Shimon ben Gamliel is not the same personality as the one in the second to last mishna as pointed out by Tosafos Yom Tov. The fact that it writes his name and doesn't say הוא היה אומר should prove this correct.

Answer 1

Maharal in Derech HaChaim end of chapter one mentions the reason for skipping both Shimon ben Hillel and Gamliel II (diYavne) was to separate between the different types of mussar in that chapter.

The chapter begins with advice for a person concerning his involvement with the world. With Rabban Gamliel begins a shift towards personal goals, so there is gap skipping between Hillel and him, to separate. That is why there is no mention of Shimon ben Hillel. With Rabban Shimon Ben Gamliel there is a return to the original theme of correcting man's actions as pertains to the outside world, so again, a gap is left where we don't mention his father Gamliel.

He also adds that the Tanna wanted to have a list of ten generations starting with Shimon Hatzadik to correspond to the ten utterances of creation.