That's a frankly insane way of looking at it. RBS didn't own the club, so it made no difference to them who it was sold to. The only thing that matters was that they are repaid in full - which happened. If the club was sold for a higher value, RBS wouldn't have made a penny extra.
The loan from RBS wasn't made in order to keep them going or because Liverpool were going bankrupt at the time of the original loan, it was made as commercial loan to the owners before they ran into trouble. RBS made a huge number of commercial loans, many of them defaulted which caused their own problems, but the loan to Liverpool wasn't made at the time RBS were in trouble, and was still a publicly listed company - the first loan being in 2007.
Accusations of insider dealings by the board also make no sense. Hicks/Gillette were forced to give full authority to the board members in order to complete their previous refinancing, which was made in order to avoid a default at the time. These board members then acted against HG when they forced the sale in order to prevent RBS taking the club into bankruptcy . HG have already tried going to court over this and comprehensively lost.
The role of the board was to act in the best interests of the club - not the shareholders (contrary to normal policy). There were no expressions of interest in buying the club that were deemed to be better than Fenway, and only HG have claimed otherwise, without providing any evidence.