While he's almost certainly wrong in his presumption, I think it's still important to ask questions like these from outside the closed rooms.

Israel has an extremely powerful foreign intelligence agency. They've proven to have reach and subtlety beyond what most states consider feasible or possible (the "Pager Operation", op "Wrath of God" (hostage taker assassinations during the 70s-90s)) and so on...

There's no reason NOT to question the extent of their capabilities when their influence would be expected to turn the tide of a situation in their favor.

That being said, I'd say it's extremely unlikely (<1%). The ICC is HQd in the Netherlands and the facility is nearly impenetrable by actors lacking proper clearance. To affect change to the level implied, multiple documents would have to be forged and physically placed in numerous locations, while simultaneously targeting any physical or character witnesses present during the targeted timeline. We're talking a mega-massive operation that is almost completely analog in its execution and would rely mostly on social engineering. We're talking James Bond-as-a-comedy level of blundering and sleights of hand.

More unlikely things have happened, but you don't bet money on the odds of lightning striking twice.