First of all, Bashir clearly stated that Odo was infected in a Stardate 49XXX, which would be in season 4, and Children of Time was season 5, so Odo clearly was infected.
Except that Odo wasn't always a changeling in that time. He was made into a solid, which eliminated the virus from his morphogenic matrix - as he no longer had a morphogenic matrix! So by the time we get to "Children of Time", Odo has had the virus removed from his body. Indeed, it would have been when Odo was judged in the great Link that he was both cured and passed the Virus on to the rest of the Link!
Odo was then re-infected at the beginning of Season Six, when he linked with the female changeling.
Seriously, why is there even a debate about this?