There are no virtually no caverns or caves open to the public in Germany. All that exists for the masses is mine diving which, in my humble opinion, is not entirely comparable to cave diving. And I don't see your point anyway. Your argument was that there are cave sidemount instructors who disallow their SM students the use of a helmet. Which I have never heard and would believe pretty much unthinkable.
A helmet in sidemount is a personal choice and it's up to each individual to decide.
You are quite right.
But I was not contradicting anything of that anyway.
First of all the point is moot as there are no caves in Germany.
Two officially, I think, a few others I know of, none allowed to be used for training of any kind, yes.
Apart from that there are cave instructors even in Germany who are proficient in sidemount. And there certainly are quite a few in other European countries and within 4-5 hours of flying/driving from where you live.
Yes, the there certainly are. I do not travel much, however.
Cave training is expensive and not being able to practice it locally makes certification (almost) useless.
If your friend is a cave instructor and not allowing his sidemount students to wear a helmet, he's essentially disallowing them to make a personal choice that affects their own safety.
In training?
I would doubt his judgment if he thought I needed a helmet for protection when training with him/her.
Now he could kindly ask them not to use any helmet mounted lights for the class, but why forbid the use of a helmet in SM?
In cave and cavern training, that includes sidemount.
It's the way it works.
Instructors rarely show flexibility in regard to their 'rules'.
As to your other friend who shocks people and puts them in awe of his wonderful helmet, does that actually work?
Worked on me, when he introduced himself to me telling me about his 10 sidemount open water dives and showing of his helmet.
He somehow forgot about a few thousand other dives, most of them sidemount, many of them trimix.
I still do not know 'officially' to this day if he is a cave instructor or even certified as a cave diver.
I wonder if it helps to impress women?
Since his has attachments to turn it into a Hello Kitty styled helmet, yes, it does
I might even get a helmet myself and scratch it up for show
Would be more funny if there weren't people who actually do things like that...