Creak in frame best practice? Has anyone troubleshooted a creak issue by  leaning the bike at an angle and pushing down at the crank at about a 6 o clock position , causing the bottom frame to kind of flex to listen for any type of creaks?.... Is this a normal method of troubleshooting because I was pissed when I saw this done to my bike.
Yes. I do exactly this to the carbon bike almost every week just to check when I hear something even resembling a possible creak... well, that is if you ignore that I actually do something similar but even more stressful for the bike every single day; every time I take a corner fast in the woods and feel the tyres losing grip.

So far checking out creaks this way has led me to tighten the BB once and to tighten the crank arms once. However usually it's actually a seat post related creak (sometimes still heard when doing the above). A quick clean and some mounting paste sorts out the post.

If this procedure actually breaks your frame or something, then be happy, very happy. You avoided a serious injury.