From results at one given temperature (300 K), Malinowski et al. [Phys. Rev. B 75, 012413 (2007)] draw the conclusion that lateral confinement of ferromagnetic-antiferromagnetic exchange-biased structures does not enhance thermally activated unpinning of the antiferromagnetic spins, which would thus contrast with a recent report [Phys. Rev. Lett. 94, 117201 (2005)], as explicitly mentioned in their manuscript. In this Comment, we discuss why such a conclusion might need revision above a "crossover temperature," as evidenced in the literature. The value of such a crossover temperature certainly depends on the magnetic parameters of each system studied, e.g., anisotropy and exchange stiffness. From the above reasons, and contrary to the statement of Malinowski et al., we rather think that their results might well agree with the report to which they refer to. In our Comment we notably aim at complementing the conclusion of Malinowski et al. by explaining why some differences between the two studies are observed at one given temperature, and why it might be expected to observe similar trends over a whole range of temperatures.
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