If it was for ALL Blu-Ray players, then it makes more sense. I understand this was just a US promotion and that's why the thread was posted.
I am assuming that margins on other Blu-Ray players are larger than the PS3 - so it would make more sense.
But if it was for the PS3 only, then it does not make too much sense.
NOTE: Manufacturers DO participate in SPECIAL OFFERS in conjunction with retailers. This happens all the time.