"This was the most logical location based on satellite pings (which was the ONLY piece of hard data related to the fate of MH370 at that time). The search area determination was not based on the pilot suicide theory.
Also, pilot suicide is the 2nd frequent cause of crashes during cruise flight (second only to terrorism), so a pilot suicide hypothesis isn't exactly "baseless". So based on past experience, a deliberate crash (either by suicide or terrorism) must be considered no less likely than a mechanical failure/fire/other technical cause."
I don't suggest it shouldn't be searched there, I would search there too but I would not search only there, if the search was spread throughout the 7th arc there would be a higher chance of spotting debris or catching something with sonar.
Pilot suicide is baseless in this case because none of the pilots had any suicidal inclinations (especially the captain as the main culprit) and because suicide in the current search area makes no sense at all whatever scenario you make.