Harrington's only chance of a seventh Ryder Cup appearance is as a captain's pick after he failed to qualify automatically for the tournament, which begins on September 28.
The two European stalwarts apparently share a frosty relationship after falling out during the 2003 Seve Trophy, when Harrington called for a referee during their singles match.
However, Olazabal has rubbished suggestions that any personal issues would influence his judgement as captain and has hinted that Harrington's potential omission would be down solely to the two-time major winner's poor form.
Olazabal said: "If people believe that that is interfering with my judgement well, first of all they're completely wrong, and if it was the case I would be failing as a captain. So that is a load of BS just to put it gently.
"If you look at the list he's well back there isn't he. Sergio [Garcia] needed a win, or to make the top three last week to make the team, he's not any different to Sergio is he? So I don't know what it's all about.
"He's an experienced player obviously, but at the moment he's not been able to deliver, period. Simple as that."