Buenas tardes Julioviana - having looked at the ILS/DME chart for Runway 01 at GCFV, it is easy to see how the B737 captain misinterpreted the altitude at which he should have commenced the procedure.
He was obviously misled by the MSA diagram on the chart which shows the MSA to the east of the FTV VOR/DME as 3000ft.
Because of this potential for confusion and because traffic separation is involved I would agree with your suggestion of reminding or instructing pilots to maintain 4000ft until leaving the FV NDB.
