I'm open to either theory, I just hope they spill the tea soon out of curiosity.
I've never worked in TV or film, but I've got to think the 2 biggest factors in any production is time and money. If we only had more time, if we only had more money, everything would have been better.
In my mind, if a prop maker was asked to make the Luke saber several things would happen:
First- He/She has to take time to research the prop (LFL archives, internet, etc..) to get the needed dimensions and understand the construction. This takes time, paid time, and it also means that prop maker is not working on something else at that time while they are researching the Luke saber.
Second- Materials have to be bought (aluminum, metal stock, specific paint (if not already available), etc.. and that cost money. Even if they have material on-hand, if you're using it for this then you can't use it for that and again, that cost money eventually.
Third- Armed with all the materials, construction begins using the Lathe/Mill and this means other props can't be made during this time while the Luke saber is being made because that equipment is being used for the day/days. Also, if the prop maker makes a mistake, a second or third prop may have to go into production to correct for errors and that's waste of time and money.
Next- This is assuming only 1 prop person is making the saber, and that person costs money. Even if they are being paid a flat fee for the job, or paid hourly (meaning it doesn't matter what that person is building they get paid the same) it does cost the production time because if you're paying them to make the Luke saber then you aren't paying them to make something else during the same time.
If multiple prop makers were needed (lathe operator, painter, finishing/weathering) then the costs would go up as multiple people are getting paid to work on the same Luke saber prop.
With so many good/accurate Luke lightsaber replicas available, and Jon/Dave aware of high-end replicas, it make way more sense to me that the Hero was purchased or borrowed because it saves so much time and money. I do think the LED stunts were probably either made from scratch or modified from existing sabers (prop dept made or fan replica).
Hopefully we'll find out eventually.