"When someone says that shaking forces are not high, how will we get assured of sanity of this assumption ?"

I wouldnt call this assumption 'insane'.Infact, you could see the recommendation of using friction clamps to resist the low dynamic vibrations in many of the mechanical response study reports.

Many stress analysts, when dealing with situations where the mechanical study requirements conflict with the thermal analysis requirements, resort to 'friction as a friend' approach after proper evaluation.