Earlier this week, 21-year-old reigning Formula Renault 3.5 champion and Dutchman Frijns complained that he will "not have much to do" in 2013.
He had told Dutch magazine Formule1 that he is not required by his new Swiss employer for the forthcoming winter test period, and it "looks unlikely I will be used during the Friday practice sessions".
"And Sauber has no simulator so I can't gain experience in that way," added Frijns.
Kaltenborn reacted to Frijn's comments by excusing his implied criticism.
"Robin is still young," she told the Swiss newspaper Blick, "so we should not place his every word on golden scales.
"He said what he said, but he is also irritated because he has not yet found a place in GP2 for this season.
"The development (programmes) for the young drivers is a real problem," Kaltenborn continued.
"The best thing for each team would be to give every reserve driver at least one go on a Friday (practice session)."