Those graduates selected as "elected" (or honorary Brothers) should not be considered "Graduate Brothers" A great article from the first Oracle clearly defined why these Brothers were selected as "elected active" (honorary) members. Remember, back then, the specific "undergraduate" Chapter selected their own "elected" members. So these elected Brothers were members of the "undergraduate" Chapter. This is confirmed several ways. First, in that same Oracle, both Alpha and Beta Chapters list their elected members. Second, in Alpha Chapter's annual picture, they frequently included those elected active Bros as part of the picture. Finally, when Carter G. Woodson died in 1950, at the Memorial Service during the 37th Grand Conclave, they listed his Chapter as "Alpha Chapter" (the Chapter where he was read in).
When graduate Chapters were formed, most of these Brothers merely continued relationship with the Fraternity through graduate Chapters since they were composed of older Brothers. Does that make them grad Bros? Yes, but it doesn't change their status on how they were brought into the Frat: as an elected/honorary Brother.
This is no different than today. For example, Shaquille O'Neal was brought into the Frat as an honorary member (i.e., through the Grand Chapter) in 1995. However, he's an active member of Tau Chapter in Atlanta (the graduate Chapter). Shaq is an honorary Brother who maintains his active membership with a graduate Chapter.
So, their status as an honorary Brother didn't change. They just fulfilled their membership obligation through a graduate Chapter.
Another example of this is the Founders. Cooper founded Mu Omega in Philly and served as it's Basileus, and maintained his membership with that Chapter throughout his lifetime. This doesn't change his designation as a Founder of the Fraternity (same for Coleman with Alpha Omega and Love with, primarily, Pi Omega).