Incitement to violence isn't always the easiest thing to secure a conviction on, what with freedom of speech concerns. But here we're talking basic license terms.
No need to secure conviction here - he's already convicted, and only out on license.
https://commonslibrary.parliament.uk/research-briefings/sn03626/
Murder carries a mandatory life sentence. This can, but rarely does, mean that the offender will spend the rest of his natural life in prison. An offender given a mandatory life sentence who is released from prison will remain on licence for the rest of his or her life.
So the question is, at what point will the probation authorities draw the line. Generally, it's pretty vague - there are hard lines on re-offending, but otherwise
"be of good behaviour and not behave in a way which undermines the purpose of the licence period".
Presumably he thinks that's vague enough that his trans shield protects him - anyone making the decision will be able to exercise enough discretion to let anything slide, as Family Guy's "oh you're transgender - in that case do whatever you want all of the time" rule.