First, murder is itself a ridiculous act, so what seems ridiculous to you is irrelevant.
Second, to assume that the purpose was to get to the interpreter is a leap on your part. The father of this family was open and up front about his heritage and views and had drawn the ire of the jihadis. If they were related to someone the jihadis might already be watching it only makes more likely that they could be found by the bad guys.
You're making a causality connection that may obscure a more relevant relationship.
The reason wasn't to stop their testimony, but rather to intimidate the other witnesses.
Intimdating a translator seems to me to be a marvelous ploy on the part of the terrorists.
And, if they kill a loudmouthed Copt to boot, I'm sure that to them it's just gravey!
Not a leap on my part. I was only commenting on the story.
Why would someone want to get at the translator? I'm sure they record testimony. If the translator goofs up or intentionally misinterprets, then they just have another translator listen to the tape and get it right.
These guys may be dumb, but I don't think they're that dumb. If they were going to bump off someone in order to impact the trial, they'd choose someone who would make a difference.