Rule 4.3 (6) states that:

(6) Stretching Devices and Training or Swing Aids.
Allowed.

Using any equipment for general stretching (other than in making a practice swing), whether the equipment is designed for stretching, for use in golf (such as an alignment rod placed across the shoulders) or for any purpose unrelated to golf (such as rubber tubing or a section of pipe).

Not Allowed.

Using any type of golf training or swing aid (such as an alignment rod or a weighted headcover or “donut”) or a non-conforming club in any way that creates a potential advantage by helping the player in preparing for or making a stroke (such as help with swing plane, grip, alignment, ball position or posture).

In short - if he is using the Orange Whip to stretch, it's legal. If he's taking swings with it, it's illegal.

True, not allowed in competition. In cool weather or for slow rounds, especially for older players not playing a competitive round should get some grace to keep moving.

Especially when waiting on every tee box, at 73 I can get stiff after a few holes, especially when the temps are 50 or lower.

Can't use practice aids. Feel free to use what you need to keep your muscles loose as long as it's not a swing aid