Currently on live, the bodyguard casts a "Reputation Check" spell when being summoned, on the PTR this has changed, as pointed out by Blazeflack on this ticket on WoWAce.

It is now the player casting two spells when summoning a bodyguard: Maintain <bodyguard name> and Summon <bodyguard name>. Below are details about the UNIT_SPELLCAST_SUCCEEDED events:

UNIT_SPELLCAST_SUCCEEDED
arg1: "player"
arg2: "Maintain Delvar Ironfist"
arg3: ""
arg4: 0
arg5: 173638

UNIT_SPELLCAST_SUCCEEDED
arg1: "player"
arg2: "Summon Delvar Ironfist"
arg3: ""
arg4: 0
arg5: 173633

These will need to be incorporated into the library to properly detect the bodyguard summon again. The relevant spell IDs should be able to be found through Wowhead.

Should be fixed in 6761120. Awaiting confirmation.

Confirmed fixed on WoWAce, closing.