I have noticed this bug on several occasions while passing through the area.
The ‘Protect the Soundless Villages from the Nightmare Court’ event is bugged such that one or more villagers will behave as though still part of the event even when the event is not active.
The ‘Help Tanaith Liberate the Soundless Prisoners’ doesn’t seem to activate – whether this is caused by the above bug is unclear.
Either way, I have not seen either event actually trigger for some time, and have spent fairly extensive periods in the area over the last few days here monitoring this issue.
The up shot is that blue moas do not currently spawn in Caledon Forest.