"I hope you realise that the poison pill can never actually be used"

I really hope that you are not an attorney since you are so blantantly incorrect.

This provision was ratified by the shareholders and would indeed manifest in the event of a non-permited bid. Such shareholder protection schemes generally do not end up playing out fully as one side or the other gives up, but most US and Canadian jurisdictions have upheld such clauses as valid.

Indeed, there is NO case where a hostile offer succeeded with the plan still in place.

If you are a lawyer, take a look at the "original case," Moran v. Household Int'l, 500 A.2d 1346 decided in 1985 in Deleware, which has been the model for subsequent decisions.