This is a really crazy BHA trip operation. The well is not static and from what I see and can guess it wasn’t static for a long time, because if they arrived at the BHA and found themselves in those conditions something didn’t go as it should have.

Fortunately, this no longer happen.

They have no choice. They have to get the collar clamp on so they can unlatch the elevators and get the lifting sub off so then they can put on TIW. Last thing you want is for your BHA to slip out of collars and go downhole.

Safety Clamp:
Consists of individual links, flexibly hinged together. Each link has a separate tapered slip which acts as a gripping member, much like a tapered rotary slip, and each slip is held in a retracted position on the taper by spring tension. When the clamp is tightened, each small slip takes a firm initial grip on the surface of the pipe.

Should the pipe start to fall, or should load increase occur against the slips, the taper mounting causes each slip to wedge tighter against the surface of the pipe to increase the grip or lock the pipe against further movement.