Well I guess you didn't read it because it has no leaks until they put oil pressure switch in. And it's a 5.4 2001 expedition Eddie Bauer edition
I would say the he read it and his advice was good and also I may say free
If it didn't leak prion to paying for a new switch to be installed I would suspect a faulty (leaky) new switch.
Now your choice would be to pay for a new adaptor as was suggested by those that charge or to try the free advice from someone that knows what they are talking about and has been on this forum for some time helping others and is very familiar with these types of problems.
Also it is very helpful when coming on the forum to give year model information as it helps that know about the many changes Ford has made over the years to give you a good response.
One thing to think about Maybe and just maybe the person that you paid to change the switch may have done something wrong and rather than admit he caused the leak he is now telling you that you need the adaptor to cover his A$$