"They concluded that the server was set to accept only incoming communication from a very small handful of IP addresses."

If it is true that there was not just communication but also ip address filters that protected this communication it would be an indicator for a ongoing and deliberate business relationship.

I think there has been an interesting pattern with Trump. His choice of Manafort (Kremlin Insider) and Cater Page (Kremlin Insider), his daughter vacationing with Putin's Family, his son involved in business ventures in Russia. Trumps dealings with Russian Oligarchs concerning Real Estate in NY and Miami.

I suppose someone might find it interesting when a Presidential candidate has a great affinity for what some consider a foreign adversary and has taken deliberate steps in changing policy to align with Kremlin's/Putin.

If Trump is elected it will be interesting to see how it plays out with the Kremlin. Is he part of a 5th column?

That there could have been some covert messaging between Trump's people and an important Russian bank ;

In other words, this seems to be more circumstantial evidence of Russians involvement in the American Presidential campaign.