I noticed this with one of my clients who processes a lot of in memory of donations. I've reproduced this on https://dmaster.demo.civicrm.org :
1. enabled in Memory of profile on https://dmaster.demo.civicrm.org/civicrm/admin/contribute/settings?action=update&reset=1&id=1
2. made a fake VISA Contribution on that Contribution page - selecting In Memory of radio button and filling in First and Last Name https://dmaster.demo.civicrm.org/civicrm/contribute/transact?reset=1&id=1
3. Result: Contact is created but is -not- marked deceased. If we had also filled out the email for the deceased (standard field for the in memory of profile) then this could easily lead to some awkward moments allowing CiviCRM to email deceased people.
4. I can understand that one may want confirmation that someone is deceased - rather than letting an anonymous donor update that field in the database - but to treat 'in memory of' contacts as alive people is risky.
5. Anyone have any suggestions on how to handle processing 'in memory of' profile submission better?