Quote from Baalzebup
Funny. I was thinking the exact same thing after I read the chapter. I did go "naah" pretty soon afterwards, since it would cause another unnecessary emo-guiltrip that is really not needed as this point of the series, but who knows...
That would be pretty bad. His mom's death is the reason he doesn't smile at all... according to Tatsuki anyway. Learning that he actually killed his mom would cause something akin to suicide I would think.