Hmmm…it seems that the common factor here is overheating of the yolk. Q.E.D. I personally use the “bathe in ice water” technique for green-free hard-boiled eggs, but your process looks to achieve the same result through different means.
And since you are a prolific poster that now is handing out cooking advice, you’re not going to start skating on thin ice and mention axe handles or anything rash, are you? 
(Link ) for those who missed Zenster’s passing.