Execution
The short synopsis of this is, they let the moment ride. CM Punk got to bask in the glory of the fans, the fans got to bask in what I'm sure was a magical moment live. Wrestling seems to be constantly moving to the next thing, illustrated most prominently by Mike Tenay's infamous TNA line "to the back." To site a less chaotic example, WWE, despite their millions of hours of weekly content, always seem to be pushing towards the next feud. Heartfelt promos are often interrupted to push to for the next feud, or, more modernly, for some dumb comedy segment, oft featuring otherwise interesting babyfaces (Sufferin' Succotash) or heels. I assure you if this were booked by the brain trust at WWE, MJF would've come out, made a joke about his UFC career, and, best case scenario, gotten GTSed, or worst case, gotten beaten down by MJF and Wardlow until another babyface made the save, taking out all the momentum out of it.
Pacing
You know CM Punk is going to be there, you know the fans are going to be chanting for him all night, so why not bring him out early? I assure you WWE would've kept Punk in the back till the main event, all the while Vince told the commentators to not mention the chants, all while the bigwigs scratched their heads, wondering, "Why are the fans ruining our shooooow?" I'm not saying fans should get what they want all the time, but have your on the fans and eyes on the rumor mill, and if something unfounded is happening, address it as soon as possible. Conversely, if the fans have you figure out, trot it out so that the whole night isn't ruined. Again, I get that there are some story things that necessitate waiting for the main event, but if it's something hotly anticipated, it's disrespectful to the other workers who have to work with that fan expectation hanging over them like a black cloud.
CM Punk himself
A very dear friend of mine began his life as a wrestling fan, admiring CM Punk because his position spoke to him, a punk rocker who didn't exactly look like the other wrestlers on WWE TV, and he brought up a very interesting point as we discussed Punk's return. In eight years, as CM Punk "Micheal Jordan's baseball career" his way through other endeavors, it was easy to fall into a hater's narrative. A bitter, unathletic nerd who walked out on the one thing that gave him even a semblance of success. But seeing that reception in a wrestling ring reminds us that he is the man to the city of Chicago, and people all over the world.
In conclusion, CM Punk's return and AEW's handling of it made me see wrestling in a whole new, fan-friendly light.