Wikipedia is particularly untrustworthy for political topics. Political parties and even nations are employing teams of people to work their way up the Wikipedia ranks in a fight for control.
Assange would know the source. Assange also made a promise to not reveal sources, making no exception for death. Giving suggestive hints would be one reasonable way to deal with the awkwardness of the situation.
Assange and his mother both hinted at it. One interview Assange did is particularly notable; he practically said the leaker was Seth Rich and then backed off a bit. It was like he was struggling with his promise to not reveal sources.
Seth Rich had the means to leak, being an IT person just like Snowden was. Seth Rich had the motive to leak, being a very upset Bernie supporter. In one of John Podesta's emails, there were some very ominous words about making an example of leakers.
There is no evidence that Seth Rich was a Bernie supporter at all, forget about being an upset one. Him being an IT person means nothing because did not have access to all DNC emails. Snowden had high level access.
Assange would know the source. Assange also made a promise to not reveal sources, making no exception for death. Giving suggestive hints would be one reasonable way to deal with the awkwardness of the situation.