It could very much be possible! Outside of the United Earth's head cities (the capital city being Vandrova, though there are a few other large ones) there are these slums--where the citizens aren't on the same drugs as those who are in the biggest hubs of population. They're like a typical ghetto, and people there are impoverished and angry, sometimes in withdrawal from the drug, and he could easily blend in with them for a short period of time. These places are policed by the Masked only when the people there get uppity and try to get into Vandrova, so he could stay there a reasonable amount of time until the Masked come in--in which case, if you like, he could be sent to one of the UE's prisons.

Their standard prison is in what is "left over France", basically, and all units are solitary confinement. If people there become too much work and they decide "you're better off dead", then he'll get exiled back to Exsilium at that point. He could also get actually killed by a Masked during a raid of the ghettos if you like, in which case he'd come back to Exsilium at that point too. With the new tablets, he could still communicate with the Initiative network in most of the ghettos but would lose his connection if he ever went into Vandrova.

Hopefully all of this is helpful... let me know if you have any questions, or like any of the options or anything!