Anyone who travels internationally and does not carry their power supplies and style adapters for every country they traverse in carryon should be seated in the rear lavs.
A more practical suggestion might be that if they're going to ask you to power up, there should be, out of the main flow, a powerpoint with a reasonable selection of adapters (US, EU, UK, Australasia and a 5V USB format power outlet would cover a pretty large proportion of travellers, I think).