I know what you mean about the quality of information available on the various websites, including the IGI when the info is "patron submitted".
All I can tell you about John Robinson is that he was related to the Taubmans and this prompted him to do a one-name study. I "met" John via this genealogy board many yrs ago. He and I communicated for a number of yrs by email and snail mail. John lived on IOM for a period of time and did his research at the Manx Museum. He did a lot of work for IOMFHS on various projects--I see his name on MI pubs, etc.
He later moved to Florida, USA. I've lost contact with him and am not certain if he is still living; the last time I was in touch with him, he wasn't well.
He sent me a detailed outline of his Taubman study which starts with Thomas Tubman abt 1480 Irton Cumberland and then the descent thru 2 sons Peter and Thomas.
A third son William Tubman was Chaplain at Castle Rushen in 1575--apparently didn't have any children.

Certainly with all genealogy it is good to verify the info one receives from others.

Donna