A couple of points to consider;
Some mobility scooters are large. How much space will it take up? Will it interfere with other residents use of the common property?
If/when the mobility scooter is left unattended who will be responsible? Sadly these very expensive mobility scooters are stolen/vandalised with monotonous regularity. Will the owner demand that the OC, i.e. other residents contribute to its replacement if stolen from common property?
Just because a person has a disability doesn’t mean they automatically get everything they need from other parties. The term ‘reasonable accommodation‘ forms a key part of what may/must be done.
Is there any reason the person can’t park their mobility scooter in their residence?
Finally, when the power point isn’t being used for the mobility scooter; will it be locked off or otherwise secured? What if someone else wants to use it and pay for the power consumed? Who gets priority?