Khabib once told that fighters peak form is at 32-33 yo. He has said that after that age, career of a fighter (lightweight) goes down. Yes, he retired for family reasons, but he was at the edge of his peak form. The same did JSP in past. Imho it is correct to retired undefeated while in prime, then turn into Fergusson or a trampoline for other young and hungry fighters, that will use you to build name or record.
I think I vaguely remember Khabib saying that, but it's not he's some sort of oracle that can't be wrong. So as much as it's true that males' physical peak (on average) falls around late 20s/early 30s, it's possible you could compensate a slight decline in testosterone/stamine etc with fighting experience, improved technique and alike. That's why it's not uncommon to see fighters (in various martial arts) in their late 30s or even early 40s to reaching for titles.
And there's some room between Khabib and Tony Ferguson. I don't think there's much value in overly focussing on retiring undefeated. In fact, there could be an element of cowardice to it, i.e. running away from a challenge, e.g. something people accuse Jon Jones of for avoiding a fight with Tom Aspinall.
Islam losing his "0" early on was probably a good thing for him. That's one less thing for him to worry about and can afford himself to take more risks etc.
Imho, with all that weight cutting, I think it will be smart for Makhachev to face Edwards, and not cut to fight Topuria. Gamrot might be a good challenge, but would that JJ and wrestling skills help, if Makhachev evaded everything Oliveira tried on him?
Yeah, there's no way Makhachev could cut down to featherweight, I was thinking more about Topuria moving up just for that fight. Although if google tells the truth, he's much shorter than an average lightweight guys, so may not be very keen on doing that.
As for Gamrot, he's much different than Oliveira when it comes to the ground game. Oliveira is pure JJ, while Gamrot is a wrestler who added JJ elements to his game.
I'd really like to see Gamrot Vs Oliveira, which makes perfect sense, but apparently Oliveira is hunting for an easier fight with Colby, as it would mean more money, plus, he wouldn't have to cut down so much, which is something he really struggles with.