The reasons why the legitimacy of Thomas Hubbarde's will and the copyhold claim of Edmund Hubbarde, his purported son, are being questioned are:
(1) An examination of the January 1573 baptismal record often claimed as being the baptismal record for Edmund Hubbarde indicates that it is actually for an Edward Hubbarde. Additional support for this proposition comes from Great Snoring records for a 1604 marriage of Edward Hubbard and subsequent baptisms of several children to Edward. There thus appears to be no record for the birth or baptism of an Edmund Hubbarde, son of Thomas Hubbarde of Great Snoring.
(2) There are records of multiple other Hubberds/Hubberts in Hingham who were contemporaries of Edmund Hubberte - Simon Hubberd, George Hubberd, Adam Hubbert, Stephen Hubbert, and Robert Hubbert - and no evidence that any of them had any connection with Great Snoring. The suspicion is that the Hubberd/Hubbert family was well settled in Hingham by 1600, that Edmund was a brother of one or more of his contemporary Hubberd/Hubberts, and thus that he originated from there instead of Great Snoring, 25 miles away.
(3) According to RJ Horace: "The style and language and spelling [of/in Thomas Hubbarde's will] all look too modern."
(4) Thomas Hubbarde's purported 1598 will makes a bequest to his wife Hellena. However, there is a burial record that suggests that she may have died in 1578.
(5) Thomas Hubbarde's purported 1598 will makes a bequest to his son Andrew. However, there is a burial record that suggests that Andrew may have died shortly after his birth in 1573. No further evidence of Andrew has been found in the Great Snoring parish records after the record of his birth and possible death.
(6) There only burial record found in Great Snoring parish records for a Thomas Hubbarde is for a burial in 1573, suggesting that Thomas may have died then and his son Edward born posthumously.
(7) The only evidence of Thomas Hubbarde's will and copyhold claim are materials contained in a 1967 report by Keith W Hubbard, which are apparently copies or transcriptions of the will and copyhold claim that were produced by "Ronald F. Kingsbury, Director of Research, Genealogical Enterprises, Norwich, England" in 1956 in response to a $150 reward ($1,400 in current dollars) offered by Kenneth Hubbard. In the past 60+ years, no one else seems to have been able to find a copy of the will and copyhold claim. The suspicion is that Ronald Kingsbury forged the will and copyhold claim in order to collect the reward.
The only way to allay the suspicions that the will and copyhold claim are forgeries is to obtain copies of them from a reputable independent source.