I'm not sure what the alternative to jail time is in these types of cases. Obviously the vast majority of sex offenders don't deserve to do "hard" time in prison, and they certainly don't deserve to be executed. So we're left with jail time, and that seems appropriate, as long as the sentence is sufficiently long.
Jail time may not be too lenient for sex offenders. Depending on the severity of the crime, it removes the offender from society. This is a severe punishment. They will not be able to prey on victims while incarcerated. If they are released, they will have to register as sex offenders, putting the community on the lookout.
If the sentence is actually carried out fully, I believe that jail time is an appropriate punishment for convicted sex offenders. I think it should be a lengthy jail time and should focus extensively on counseling and rehabilitation. I think capital punishment should only be used in extreme cases. Removing sex offenders from society for an extended amount of time is a punishment fitting of the crime.
No, jail time is not lenient. Although it should be a lengthy sentence to fit the crime. More accurately, it should be prison time. Sex offenders should spend a specified length of time in prison for the crimes that they've committed. Something like community service is not enough. There should also be mandatory behavior modification programs for these prisoners.