Iff you care about making a good presentation, it's crucial to NEVER put your hands in your pockets during presentations. It's also crucial to EMPTY YOUR POCKETS before delivering a presentation.
It communicates low-confidence, low social status, and low effort/energy/caring for the topic and audience!
Why empty your pockets before delivering a presentation? Because so many presentations are ruined by hands going into pockets, jingling keys, jingling change, cell phones going off, etc. Items in pockets will become distractions, and you don't want to be distracted (again iff you care about making a good presentation).
Default hand position during a presentation should be arms at side with elbows bent 90 degrees, hands outstretched. To communicate friendliness, warmth, enthusiasm, and confidence, use expansive gestures by going wider from the default hand position and making overhead gestures occasionally, smile, tilt your head, and don't be stiff or robotic. A relaxed but upright posture. NEVER cross your arms, put them in your pockets, put them behind your back, cover your crotch (the Adam and Eve pose). Don't point with a finger, point with a hand. Use palms-up (assertive/submissive/friendly) gestures whenever possible, and avoid palms-down (dominant/unfriendly). Sometimes, you can emphasize or punctuate a critical point with a dominant body language, and it shows tremendous confidence. But don't overdo it, or you seem unfriendly.
Watch good presenters and politicians. You will notice they never put their hands in their pockets while speaking/presenting. Maybe they pull something out of a pocket dramatically to demonstrate something. They never have anything in their pockets for their fingers to wander off and jingle.
I abstain from comment on what you heard "through the grapevine", and you shouldn't care about gossip and rumors, either.