Yep I think it’s quite a smart play by Poundland. It’s cheeky enough to tap into people with a certain sense of humour, the polar opposite of most Christmas marketing so bound to get attention and be shared, and if the overwhelming response to the first messages was negative with no +ve reinforcement, easy to drop the campaign.
I found the tweets most amusing. I expect that they took the punt based on knowing their audience and making a judgment call that the humour would be welcomed.