why not reinstate it, ask dellam to create a complex password for example (dont actually use this dellam) "W4rcr4ft2!@#" and see if any hacking occurs on the name. if it does, you know it was dellam and not someone who cracked his password that consisted of a space bar and nothing else.
if hes hacking he's gonna do it whether he has the dellam name or not.. i personally dont feel like there is solid proof dellam ever actually hacked.