Forbes is owned by multi-milionarie Republican (demi-Libertarian) Steve Forbes. It is not a friend of Democrats in general, and Liberal Democratic icons like Ted Kennedy in particular. Still, it was restrained and friendly compared to some other right-wing sources.
The letter the article refers to did appear to happen. The hostile analysis you quoted though, is just that. There's nothing in the letter itself about a "quid pro quo", and no request for help in the upcomming election. If anything, Kennedy seems to be saying he'd have credibility on the subject precisely because he wasn't running in the upcomming cycle ('84).
Another perfectly reasonable cynical political interpretation of this letter is that Kennedy felt that anti-Soviet feeling strengthened Reagan's hand, so anything he could do to help promote understanding and cool tensions would therby weaken Reagan.
Here's what Kennedy's wiki page says about this incident:
Kennedy became the Senate's leading advocate for a nuclear
freeze and was a critic of Reagan's confrontational policies
toward the Soviet Union. A 1983 memorandum from KGB
Chairman Viktor Chebrikov to General Secretary Yuri Andropov noted
this stance and asserted that Kennedy, through former Senator John
Tunney's discussions with Soviet contacts, had suggested that
U.S.-Soviet relations might be improved if Kennedy and Andropov could
meet in person to discuss arms control issues and if top Soviet
officials, via Kennedy's help, were able to address the American
public through the U.S. news media. Andropov was unimpressed by
the idea.
So why the conspiracy theory? Well, perhaps part of the reason is that there was at that time a similar story going around about Reagan doing that exact thing to Carter in 1980 (with Iran). So the foreign conspiracy story was already out there. All that needed to be done was change a few names.