Dispelling in CH should put you into PVP combat

[Startuptimpa-benediction]

The CN guards are heavily bugged. There is a known exploit to cause guards to attack peaceful and even afk enemy faction players at no harm to you:

https://us.forums.blizzard.com/en/wow/t/exploit-summoning-infernal-on-non-flagged-players-in-cenarion-hold-causes-guards-to-attack-non-flagged-players