I just tried. Pulling as hard as I can, no movement. While I admit I'm still somewhat new to this, I used my dad's SLR back in the mid 90's without issue, and never had an issue popping the back of the AE-1, or the Yashica MG-1, or Nikon FA. Just seems odd to me.
And of course, stinks knowing even if I get the film out...it's probably already ruined, or will be if it's sitting there waiting to be exposed. I had intended this to be a test roll, but I still don't like losing images. Such is life though.