Sinar Parman and Steve "Sarge" Pfauth have both reported he was never even allowed on site at Winter Headquarters in La Quinta ("Rifle" was Hubbard's personal residence at site). Steve Pfauth reported the McSavage wasn't even allowed to know where the Creston Ranch site was located (until after Hubbard's death) - the reason for both of these given as Hubbard didn't trust McSavage.
Jesse Prince confirmed McSavage was not trusted by Hubbard as early as 1981, when Hubbard ordered a Sec Check to be done regarding why McSavage was trying to cut Hubbard off from corporate control. David Mayo confirmed this sec check was ordered, too.
The only first-hand source claiming McSavage was any kind of protege or apprentice of Ron Hubbard was McSavage himself!