This is the case with the underscores, yes. The username was "fus__ro_dah"; anyone paying attention should be able to tell that the first underscore is longer than the last one. Not looking at why that could be seems like a lack of effort/curiosity on the part of the people with access to the message logs.

Similarly, there's a recording of the actual perpetrator's voice in evidence, but "over seven years after it was obtained by police, no attempt has been made to analyze it or to compare it to any person’s voice."

This isn't about technical literacy so much as just laziness.