I didn't know the Chelsea Russell case was also without jury. I think I tried to find out at the time, but couldn't find any information about it. It makes sense - it would be difficult to find a jury willing to convict, unless you found a way to stack it with SJWs. It wouldn't even be nullification, I think. The wording of "grossly offensive" is vague enough for any jury member to go "well I wasn't offended, so I don't think it's grossly offensive".
This trial without jury thing is a whole other layer of horrible. It was originally introduced to deal with cases of gang-related crime, the fear being that other members of the defendant's gang might get to the jury and intimidate them. But of course, once established, the scope of it expanded, as these things always do.
Chelsea Russell wasn't tried in the absence of a jury due to any legislation relating to gangs. She was tried in a magistrates court (I. E a court that doesn't have a jury and has either has a bench or two/three lay magistrates or a single district judge) because the offence she was charged with is an 'either way' offence which can be tried in either a magistrates court or a crown court.
With the latter being the one with the jury. (and it was a summary only offence only trialable in magistrates for offences prior to the 13th of April 2015)
Chelsea could have elected for trial by jury for her case but she would have run the risk of a more severe sentence if found guilty and also higher costs in a crown court trial.
Summary (magistrates) trials are very common in the UK and are used to try most traffic offences and lots of assaults (common asaault/assault by beating are summary only offence) , thefts, criminal damage and offences of a similiar mavity.
So there is nothing unusual in the mode of trial employed here.
I suspect she was likely following legal advice when she decided not to elect a crown court trial.