Not appropriate for a soldier?

[Yaish]

Two issues:

First, military service is about obeying the lawful orders of your superiors. If the officer in question has the authority to determine proper dress for civilian attire, then its a lawful order. Normally in the US this authority rests with a base Commanding General, who issues such orders or delegates that authority to Unit Commanders. For example, in the US Marines wearing tank tops or untucked shirts is against regulations, as is not wearing a belt in any item with belt loops.
If the officer in question lacks that authority then piss on him, its not a lawful order. If he tries to give a subordinate any problems because of it he could get in trouble. (and here the real world enters into play: He can probably make your life hell and get away with it, and you can probably complain but without a sympathetic commander good luck)

Now, the second point. Yes its true that military members agree to adhere to and follow a second set of laws and rules. In the US its the UCMJ, I'm sure other countries have their own versions. However, anyone who thinks they are living free and clear of any authority because they arent in the military is sadly deluded.
Try walking down the street naked.
Try walking into your neighbors house (naked or not, I dont care) and taking their home theater system.
Try driving with the pedal to the floor as you go down the freeway.
Try ignoring the tax collector.

I'm sure you get the picture. You've just gotten used to the rules and authority you are familiar with and rarely recognize it. For long term military members its much the same thing. You feel just as 'free' once you've gotten used to the rules. For the most part the difference in the level of authority over civilians and the military is merely a matter of appearances. (with a few granted large exceptions)

[davedove]

I don't know how it is in Finland, but in the US commanders (I can't say how far down the authority falls) can dictate how a soldier dresses, even in civilian attire. Granted, it isn't pushed most of the time, but if attire is deemed "unsuitable" it can be barred from wear.

It sounds to me like the commander in question suffers the same misunderstanding of the kilt as most of the populace.

[James]

It might not be written down, but there is a tacit understanding when accepting commissioned rank that one will adhere to certain codes of behaviour.

That includes such things as the manner of dressing: and I well recall how just as I was required to obtain my uniforms, hats etc, from specified tailors, because my regiment required certain styles of cut, and colour. I was also required to adhere to a certain off duty dress code.

This all might seem overly restrictive to some: but it is a part of the ethos of the officer corps of any army, and oddly enough enhances the fighting ability of that army. For it is a shared thing amongst the soldiers of say a regiment, a part of what binds together first the officers, and then the other ranks.

Now such things as the adherence to an off duty/civilian attire dress code, might appear ridiculous in this day and age: but it is also linked to the very necessary discipline, which also binds a unit together when life gets too interesting.

So rather than quibbling about not being allowed to wear the kilt when as I understand it carrying out a military duty: the attitude should be of pride in holding a commission, in an army of high repute.

It is some years since I was a serving officer, but if time travel was possible-and I had to serve again: I would hope it was with an army which insisted on the preservation of such standards.

James