Agree with the fact that there are so many out there who are willing to take this up even without a pay. But given the history of the org and also just throwing out an assignment and scouting for ideas/entries is something I am totally against no matter whichever org it is. Even if there are a thousand entries being sent for this role do you think the org is going to acknowledge and reply to every entry with a feedback? I don't think so.
Any org that gives an assignment upfront is a huge red flag IMO. You're literally wasting the time of so many candidates out there who is living with high hopes of cracking it.