From Wikipedia:
Webb's ex-wife, Susan Bell, told reporters that she believed Webb had died by suicide.[74] "The way he was acting it would be hard for me to believe it was anything but suicide," she said. According to Bell, Webb had been unhappy for some time over his inability to get a job at another major newspaper. He had sold his house the week before his death because he was unable to afford the mortgage.[74]
I think the inclusion of the implication that murder is covered up does more harm to his legacy. Many people will throw the baby out with the bathwater.
Edit:
Also, contemporary reporting says he left four suicide notes, instructions on the door to call 9/11, organised cremation paperwork and personal items for family.
Also, surviving point blank gunshot suicides are not unheard of. Rare; not impossible.