So, the friend is going to rent it out. Which means, if that's a success, that a batch of landlubbers and unskilled tourists may be sleeping and having drunk parties on the boat every night of the year. (One can hope. But hey, maybe it will be booked by church choirs on tour.)
Now what happens if the pitting turns into a leak and worst case, someone drowns? Eh, yeah, you can't rent it out again until you get the bodies off the boat. Bummer.
I wouldn't call it terribly irrational or unresponsible to have a 20 year old aluminum
hull professionally surveyed, and to have some welding done where or if needed. Then apply the right anticorrosion paint, anodes, whatever will keep that boat in prime condition.
But that's just me. A real wastrel when it comes to things like money
and boat maintenance