Hillary says Tulsi Gabbard has Russian backing. That doesn't make Tulsi a Russian asset, only her collaboration with them would be evil.
Gabbard seems to advocate a non-interventionist foreign policy, so does Rand Paul; it is easy to see how that would appeal to every foreign nation which opposes the U.S. That coincidentally is a list of our current enemies, and would include Russia, China, Iran, and perhaps less active players like Cuba, Nicaragua, Bolivia, North Korea, Belarus, and Turkey.
While not my choice, isolationism is not treason; particularly for a nation situated like the U.S. or New Zealand where geographic isolation makes it a valid policy option. Let me repeat something I wrote during the 2016 presidential campaign.
Republicans are not to blame if those of the far right find them preferable to Democrats. Likewise, Democrats are not to blame if those of the far left find them preferable to Republicans. Nobody can control what or whom others find preferable.
In a system like ours that is practically (if not technically) two-party, extremists normally back the party whose platform is marginally nearer to their preferred policy. In doing so they vote for the lesser of two evils. Don't we all face this dilemma at least some of the time?
I voted for McCain (2008) and Romney (2012); 20-20 hindsight suggests they'd have been as bad in office as Obama turned out to be. When I voted I believed there was a chance that was not the case. (Full disclosure: If we have a loser as president, I prefer he or she is a Democrat.)