It's been like that for years. Many, many flights. Never a problem. I used to book my own travel at Megacorp, and our booking system only transferred a middle initial to the airlines. That was never a problem. That's why I posted about this. I looked into it years ago, and actually found something on the TSA website confirming that it didn't matter. No, I don't have a link but I imagine if somebody was really concerned that they could find it as well.
To your point, I also have my middle name properly documented on real ID license, passport, etc. It's just that travel companies don't do a good/consistent job with middle names, so TSA, etc. doesn't seem to require them. YMMV.