+1 noted! I'm guessing you missed out a "not" in your second comment :-)
The reason it's not done yet is because there are a lot of things that people have asked us to add to PythonAnywhere -- our list of suggestions is thousands of items long -- and we're adding things based on how many people have asked for them. Support for task queues like RabbitMQ and Celery only reached the top of the list relatively recently, and there's a lot of stuff we have to do to support them. The first step was always-on tasks, which we released officially near the end of last year, but there's still more to do.