Poppy, there may be a bit of a misunderstanding about what summary judgment means. (Or perhaps not; of course, you are quite entitled to your opinion either way.)
A summary judgment means that even if all of the Other Side's assertions are true, there is still a 100% chance My Side would win at trial. Naturally, to make this determination, a judge has to consider this request as if all of Other Side's assertions are true.
It's no more saying that they think DM's assertions are all true than it is saying they think every last one is utter bunk. I can't think of a situation where being granted summary judgment would be considered embarrassing. It's a judge's ruling that Other Side's defense was, quite literally, admitting the offense.
I am not familiar with the rules of ethics in the UK, but I would venture a guess it violates them not to file for summary judgment if you hold a belief that your client is entitled to it.