There's no need or reason to talk further with you if you honestly believe pulling the PDFs of OOP editions had anything to do with battling piracy.
I don't think anybody actually believes that. Clearly, there is some other motive at hand or perhaps multiple motives. Some possibilities (some combinations are possible):
1) Desiring to bring PDF publishing in-house, WotC might have thought that yanking their PDFs from established distributors for that reason might generate some ill will among consumers, so they decided to make it coincide with some piracy lawsuits and blame it on piracy, believing that people would be sympathetic to the move on that account.
2) WotC has decided that OOP PDF products compete with 4E sales and has decided to pull them for that reason.
3) WotC has decided to send a message to GSL-using companies that their business is not safe and that they cannot rely on WotC goodwill or reasonableness not to cancel their license abruptly and capriciously at a whim. The message is: "Get out of this market or else!" This might be part of a strategy of 'reclosing' the system and delivering a blow to open gaming, but without actually yanking the GSL itself, which would have generated consumer outrage.
*Note: If it was a strategy to deflect consumer outrage by blaming the move on piracy to mask the real move, WotC has clearly miscalculated the level of anger their policy would generate. It may, however, still have been less anger than what they would have incurred if they had stated the real reason for the move.
There might be other reasons as to why WotC did what it did, but 'fighting piracy' does not even figure on my list of possibilities, because that would be so mind-bogglingly stupid and ineffectual (and actually likely to increase piracy) that it just cannot be.