These high costs are because of money spent on defence lawyers? Fascinating. I suppose one wouldn't risk any but the most expensive lawyers lest one end up losing to this guy.
What a shame it would be to lose a transparently baseless case through mismanagement. Ironically, it's the strong cases that you're almost sure to lose that you might as well phone in or not defend at all.
In this case the plaintiff does everything he can to jack up the costs, including bombing the case with irrelevant stuff, gaslighting, etc. The courts have caught him doing this in other cases and chasized him in their rulings (complaining for forgeries and perjury) but the recourse so far has been confined to wrist-slap grade consequences.
A lot of the structure we have in our courts (both in the US and UK) to ensure good faith behavior is setting things up so that cheating makes you ultimately lose the case. But if you didn't seriously expect to win on the merits (instead only by the other side screwing up) and were mostly just trying to use the process to cause harm then it doesn't really matter if your forgeries and perjury ultimately cause you to lose.