To clarify ‘any Air Traffic Control measures’ causing the slot violation (especially in relation to full freight operations), will ATC decision for late push-back due to heavy passenger aircraft traffic be considered as ‘Any ATC measure causing slot violation’?

Yes, this can be a justification if the violation occurred due to following an authorized official order. It is upon the airline appealing for justification, to prove the causality of the ATC decision and the night slot violation. The ILT evaluates each case individually.

See also article 4.1.d of the Policy Rule.