I think I remember there was a problem in 2019.. is that charge of $6,000 refundable when they cancel 2 days before the event? The announcement was made Thursday.
Cobb parks generally work with civic groups and aren't out to gouge.
As far as the crime comments, this is miles from the Stadium Crime Zone aka Truist Park and is generally safe. Cobb PD rangers are on site. The jail and sheriff's office are 1 block over. Other than some five finger discounting, crime is virtually non-existent. Cobb=Count On Being Busted. This isn't the City of Atlanta.
The Atlanta hamfest has been on the rocks since the 1990s, they've been at:
Atlanta City Hall East (before it was demolished and replaced with Ponce City Market)
The Airport Hilton (Alanta HJIA)
Cobb Galleria Centre
Jim R Miller Park (on and off since the late 1990s) when they "combined" with the Kennehoochee Amateur Radio Club (who always used JR Miller since the beginning of time)
Honestly the ARC has a lot going on. Their repeater is also failing and the landlord isn't exactly warm and fuzzy (which is why hams need to be good guests when on free rides on vertical real estate). Not saying they are at fault, just stating facts. The ATL hamfest has been in decline for two decades.