  Recently, Castellano and Pastor-Satorras [1] utilized the finite size scaling
(FSS) theory to analyze simulation data for the contact process (CP) on
scale-free networks (SFNs) and claimed that its absorbing critical behavior is
not consistent with the mean-field (MF) prediction. Furthermore, they pointed
out large density fluctuations at highly connected vertices as a possible
origin for non-MF critical behavior. In this Comment, we propose a scaling
theory for relative density fluctuations in the spirit of the MF theory, which
turns out to explain simulation data perfectly well. We also measure the value
of the critical density decay exponent, which agrees well with the MF
prediction. Our results strongly support that the CP on SFNs still exhibits a
MF-type critical behavior.
