I've since discovered that there is proof that a Captain Mathew Campbell, merchant in Glasgow married Magdalene Kinloch, sister to Sir Francis Kinloch of Gilmerton on 25 December 1710 at Edinburgh.
It's in the Edinburgh Marriage Register on page 91 and it can also be found in the ScotlandsPeople website. The ScotlandsPeople website also has baptisms for at least 4 children; a son John, baptised 19 Feb 1712 and three daughters; Mary, baptised 16 June 1713, Jean, baptised 10 Feb 1715 and Elizabeth, baptised 8 Oct 1716.
Captain Matthew Campbell, must have died before 20 April 1729 because that's the date his widow married Francis Dunlop or Dunlap of that Ilk according to page 166 of Edinburgh Marriage Register.
The History of Parliament article for Daniel Campbell, 3rd son of Walter Campbell, Captain of Skipness, mentions he was often in partnership with his brother Matthew (in the first paragraph) and Matthew must have been younger than Daniel, because the article for their brother John indicates he is the second son, and presumably Angus who succeeded to Skipness as in The Heraldry of the Campbells I've referred to in my original question, is the eldest son.
So Matthew Campbell, son of Walter Campbell of Skipness, has to have been born after 1672 (and can't be Matthew Campbell Rhea, who is fighting in a rebellion in 1685).
It seems likely that The Heraldry of the Campbells is correct and this Matthew Campbell married Magdalene Kinloch in 1710, had from other sources had 4 children and died before 1729. Something else I saw suggested that Matthew Campbell wasn't just a merchant, but Captain of a merchant ship.
So if we merge the Campbell and Rhea profiles, do we then create a new profile for the real Matthew Campbell? And disconnect Magdalene Kinloch from Campbell Rhea and connect up to that profile?