There's no guarantee that it is food safe. HDPE 2 is a certfied food safe if the processes and materials used are food safe (and when the FDA approves it)*. I've read comments/statements that make convincing arguments for and against the homer buckets. What it comes down to is you need to read both arguments and do what you're comfortable with.
Having said that, I think you should keep it. You don't have much more to lose at this point.
On a side note... I was in a port-o-john recently and I was happy to see that the wall was stamped HDPE 2. Would you ferment in that? I don't think they made that plastic to be food safe. I mean, it is meant to hold food, but... after it is processed by us (gross)
*(no quote/link here, just read all the other threads beating this to death)