This.
Teachers often call their students “guys”.
It implies a casual non-threatening relationship, and to be honest, used when a teacher who sees/knows many students can’t quite remember names at a given moment. A teacher would say “Ok guys, let’s all sit down and turn to page 27.”
A teacher would have been off on the school holiday that terrible day in February 2017 just like Abby & Libby were. Were Delphi schools off yesterday, Easter Monday? Schools in my area were out. If Delphi schools were out, the presser could have been strategically scheduled for a school holiday after inviting the public to attend. That would allow a teacher to attend. If the families were told the perp could have been a local teacher, that would be shocking and upsetting to them.
I am a teacher, and as much as this theory troubles me, it is preferable to me than the thought of a family member or LE being involved.