To be honest there is not much the other pilot can do about it. By the time the flare hasn't happened it is too late and a pile driver is going to happen no matter what. In some types a last minute tug on the stick can actually make things worse by rotating the main gear into the ground.
Only one thing is certain, no matter how experienced you are they still happen, they may get rarer but no one is immune. I must be due one coz it's been a while now!.