The paradox tells them that the perpetrators used a Time-Turner to send messages back in time. TTs are generally locked to a single person’s use; someone else can’t come along, steal or take the TT by force, and use it for themselves. They explicitly say they suspect someone might have forced Harry to use his TT in this way. They are fools not to check if someone forced or tricked another child to use their TT.
Also, they check if Harry can still use his TT that day because they suspect him. But they do not treat him as an adversary. Flitwick doesn’t question him closely to make sure the Harry in front of him really just came back 6 hours in time. It would be trivial to ask him questions interactively to prove that, instead of just have him pass a message. Minerva should have had the message say: “Filius, please question Harry to make extremely sure that he just came back 6 hours in time!”
Indeed, Dumbledore and his allies are being somewhat less than maximally clever here… it would make more sense if they simply didn’t know about the other student with a Time Turner because it was an unauthorized copy, or something. (And it’s quite apparent that Time Turners are far more common in the MoR-verse than in canon, Hermione was only able to get one in book 3 was said to be a very unusual event which was only happened because the staff had an extraordinarily high level of trust in her.)
The paradox tells them that the perpetrators used a Time-Turner to send messages back in time. TTs are generally locked to a single person’s use; someone else can’t come along, steal or take the TT by force, and use it for themselves. They explicitly say they suspect someone might have forced Harry to use his TT in this way. They are fools not to check if someone forced or tricked another child to use their TT.
Also, they check if Harry can still use his TT that day because they suspect him. But they do not treat him as an adversary. Flitwick doesn’t question him closely to make sure the Harry in front of him really just came back 6 hours in time. It would be trivial to ask him questions interactively to prove that, instead of just have him pass a message. Minerva should have had the message say: “Filius, please question Harry to make extremely sure that he just came back 6 hours in time!”
Indeed, Dumbledore and his allies are being somewhat less than maximally clever here… it would make more sense if they simply didn’t know about the other student with a Time Turner because it was an unauthorized copy, or something. (And it’s quite apparent that Time Turners are far more common in the MoR-verse than in canon, Hermione was only able to get one in book 3 was said to be a very unusual event which was only happened because the staff had an extraordinarily high level of trust in her.)