Echoing the comments about it being a person or an organization! This would be a great addition if both are possible options.
Just to back up the point it could be a person or an organisation and it would be a nice property to be able to use.
Allow a person or organization - Some settlements aren't founded by one person but by a group.
Have to agree with Snake_Venom, allow it to be a Person or Organization and I'm for it
I'd like to see the amendment that it can be multiple founders, as it could be a family or adventuring party.