Well in the UK it would be based on sentence. I'm not sure of the usual severity of sentence for rape, but imprisonment is quite common and I think of a length to often never be spent. I think many would consider it a serious enough offence that you can't simply "move on" from it. Rape and murder probably should not be forgotten, bar room brawls at 19 probably should. The laws seem to try and have some awareness of that nuance.

A sentence of over 4 years prison, including suspended, would never be spent. Prison for six months would be considered spent after 2 years. However, sex offences are an exception covered by the sex offence register, which gives a different time line. 10 years or life I think, again depending on severity of sentence.

Thus he'd not be rehabilitated and forgotten by UK law until 2025 I think, so should not really be getting the right to be forgotten - it's too current.

The rehabilitation law itself covers insurance, employment, housing, media and so forth and has no awareness of any new media as it's from long before them. So it would solve the indirection via obfuscation: An old, spent, offence would be buried in some newspaper and court archives and probably only surface if someone was dedicated to digging into their background.

The EU right to be forgotten seems like a valiant, if perhaps a little clumsy, attempt to achieve a similar effect.