Time of loss or not, rules need to be followed.
However, as Catholics, they may not have known the rules. If I went into a church I was unfamiliar with, I would not walk around, at will.
Often times, even in Orthodox churches, I first ask permission to take photos, or to walk inside, when everyone has left.
It's simple courtesy.
I am sure you did it in a polite and non-threatening manner. They simply didn't know.
It was a great opportunity to educate them. Were they just curious, or were they being nosey or offensive?
Either way, seeing them entering the Altar would made me go ballistic!
Stashko, I would have done the same thing!
Lord have mercy on us both! I am very defensive of Orthodoxy!