During the rush hour London commute, Non-folding bicycles are not allowed on the train service. However there has been a rise in people bringing non- or only partially folding electric scooters on my regular commute. Whilst the green credentials I'm sure are admiral, the size of these scooters are a menace. Are these really permitted to be carried on peak services?
Guard's discretion I suspect. As they aren't legal to use in the UK., it's unlikely that SWR will have a policy. Have you tried asking a guard?