That was dumb. If they come off as being motivated more by personal animus or anti-trans sentiment than by the injuries they suffered, it may make it harder for them to prevail. They should ask JY how well his own racism worked out for him at the BCHRT.
JY hasn't legally changed his name, so they are referring to him correctly. In fact, by adding the AKA they're signaling their intent to call him by his colloquial name whilst the legal action commences.
"Dead naming" may be a thing on twitter, but in legal proceedings it is ones legal name that prevails, though parties are free to use an adopted name if agreed upon. But, as far as the state is concern, his name is Jonathan Yaniv