I think that mechanic needs to stick to working on the ford tractors.
Running a jumper from the MAP can really only do one of 3 things:
1) make the PCM believe that the MAP sensor is maxed out and seeing 51psi boost (page 63 of the bible)
2) make the PCM believe that the MAP sensor is putting out 0v and therefore seeing no voltage (page 63 of the bible)
3) make your wallet see low by shorting out something expensive
I have to think that if the PCM were to see a 51psi signal it would take protective measures; likely not even run nor start. Remember, with a fixed jumper it would see the signal ALL THE TIME and I doubt that it would pass sensor validation at startup.
I suspect that if it saw 0 psi it would either permit a dangerous overboost situation and never know it or it would fault upon start up because it sees no atmoshperic pressure (it's unclear whether that sensor is an absolute pressure sensor or a gage pressure sensor and therefore just measuring pressure above atmospheric)
Either way, with the complexity of our trucks, I just can't see a jumper wire in a circuit designed for a variable voltage as beeing an OK thing to do.
I do agree that with some older EFI systems that there was the ability to make some sensors read max or min and acheive some benefit, but that was waaaay long ago.
PS: no comments in this post were intended as disparaging against tractor mechanics