I’m struggling to understand why he thinks being vegan has anything to do with his dismissal. It really hasn’t. They don’t have a problem with him being vegan, they probably (guessing here but it seems reasonable) don’t have a problem with him asking about and questioning what investments they make.
However it sounds like he made a complete chunk of himself and went way beyond what is reasonable and what he did constituted gross misconduct.
GM is normally pretty cut and dried eg violence, doing things which intentionally damage company property, bringing company into disrepute, those sorts of things.
The LACS seem pretty relaxed about it and I can see why as his veganism is a complete red herring.

keep it up piers, your doing a grand job

Whereas you’re repeating the same boring joke, over and over. Bet you’re dead pleased with yourself.

This case seems especially odd, as Maya Forstater lost her job last month for refusing to believe that people can change from one sex to the other:

https://www.bbc.co.uk/news/uk-50858919

Bet you’re dead pleased with yourself.

not seeing this when i look in the mirror

why wouldn’t i be ?

No wonder you don’t see it, you’re on the opposite side of the same coin.

You know what, it’s been fun but I’m bored now. What’s that saying? ‘Never try to argue or reason with idiots. They bring you down to their level, then beat you with experience.’

But tom, calling someone Piers Morgan over and over again is the height of sophisticated argument and intellectual debate.
I think you’re probably just not clever enough to understand it.

keep it up piers, your doing a grand job

Still working your way through the stock of Christmas and New Year booze, then; one clear symptom of a drunk is their habit of repeating the same thing over and over again, a habit I’m seeing here.
Time to go to bed, son, sleep it off.

his veganism is a complete red herring

Is it just beefed up vegetarianism?

This guy knows what he’s doing. He has committed gross misconduct and knows it.

So he’s taking the opportunity to gain some benefit for his cause by asking the court to establish, as a precursor to the main question (of his conduct), whether being a vegan brings rights as a belief system. That has been confirmed.

He cares not for the rest of the trial I’d guess.

In short, it’s quite a smart way of getting a principle established in law.

Plants are massively complex and evolved structures and have demonstrated sentience, so why does there not seem to be a group of individuals who would seek not to eat them