Like any good druid, at lvl 10 I used Teleport: Moonglade. I was immediately killed repeatedly by horde.
For science, I ensured I was not PvP flagged and went a second time, in case I had accidentally flagged myself for PvP. I am sure I didn’t attack anyone and once again, I was flagged for PvP in Moonglade upon arrival.
I observed characters arriving to Moonglade and all are PvP flagged. There’s a nice pile of skeletons next to Dendrite Starblaze 
Are you playing on the “Normal” ruleset? If you’re on the PvP ruleset this isn’t a bug — Moonglade has always been a contested zone on PvP servers.
Moonglade is contested territory in PvP servers. However the guards should be at least attempting to keep the peace, but if I remember right in Vanilla, the guards have a lot of blind spots.
You aren’t flagged on a pve ruleset and you should be flagged on the PVP ruleset. Because of being realmless all opposing factions show as yellow on the PVE ruleset and flagged people show as orange. If both are flagged you will show as red to each other.