Unless you believe the author of that comment is a member of the extremely violent MS-13 gang there is no threat being made there.
English as 2nd (or 3rd) language for you?
If someone stuffed your mailbox with pictures of your kids, as well as others who have been brutally murdered, you’d think “Isn’t that sweet of them to include pix of my kids”, and not see a barely veiled threat?
I call BS.