As they say "There's three sides to every story, your side, their side, and the truth".
Now I just want to state I am categorically NOT saying your DD is a bully but I just wanted to add my twopennysworth.
When DD was being bullied at her last school, the bullys Mum believed THEIR version of events, including the bits where my DD was apparently threatening to heat the crap put it him every night, this is the same DD who wouldn't say boo to a goose. The truth in fact, was the other way around, they'd been threatening my DD, but it didn't matter, she believed him.
Firstly, I wouldn't outrightly believe my DD, even after all she's been through there was a incident between her and another child, it turned out to be a case of six of one and half a dozen of the other. I did not choose to believe DDs version outright. I listened to both sides, as did the school, apologies were made and it's all been sorted.
In all honestly, I'd check what the other child's version of events were first, it just seems way OTT to threaten a child with 'there will be consequences' over something as trivial as teasing about liking a boy. Any teacher or lunchtime staff worth their salt will tell you this is practically a daily thing.
If it's established that there is all there is to it then it's clear hes just trying to be intimidating, and I'd make school aware just to put it on their radar.