It’s bullshit. Springboard has a facility to show notification bubbles showing Unicode text. There have been a lot of issues in Apples libraries where it turns out that if you render certain strings, the process crashes or hangs. If such a string is in a notification bubble Springboard crashes or hangs. If Springboard hangs or crashes repeatedly you have a problem. That’s bad but has nothing to do with iMessage or SMS, that’s just used to pop up a notification with invalid text.