I would not go so far as to say 'playboy' in connection with Anderson's derisive opinion of Macnaghten. More likely 'coward' which is much stronger and more offensive.
For that is is the only un-named reference to Macnaghten [according to Swanson's other annotation] in Anderson's memoirs. Imagine you are the Assistant Commissioner and that old coot has brought out his laughably vain memoirs and the only reference to yourself, after a dozen years of serving under that old coot, is the tiny but extremebly bitchy mention of a senior policeman who was frantic over some threatening correspondence.
Mac saw himself as the Action Man, the Etonian Super-Cop, rushing to the scene of every major crime. He even had that poor, innocent, wrongly convicted Adolf Beck over for tea in his own home.
So this was a low blow by Anderson in 1910. Even if true, Macnaghten's service as a top cop amounted to more than that, amd yet this is the only reference. Mac responded in his own memoirs by dedicating them to Anderson's successor, the finest cop he ever knew, and not mentioning his loathed predecssor at all. He also of course wrote very differently about the Ripper too -- for an entire chapter!
Oh yeah the fiend's identity was pretty close to a 'definitely ascertained fact' alright, it is just that Scotland Yard did not zero in on him until 'some years after' he suicided. They had some facts about the chief suspect but were too incompetent to follow them up. He makes it very clear that he himself was not responsible for this blunder, but takes credit for 'laying the ghost' of the murderer at some future date.
Macnaghten also poignantly claims that he went down to Whitechapel and felt compassion for the harlots he met with, and gives all the victims at least the dignity of their names. By contrast, Anderson does not name them, and pretty much blames these 'criminals' for their own deaths at the hands of this minor, tabloid-enlarged maniac.
Macnaghten pictures the Ripper as an omnipotent, sexually-insane madman, an East End Nero, one who could look a perfectly ordinary person in a London crowd, and who made government officials tremble -- and even resign. Macnaghten further twists the knife into Anderson by making ti clear that the police were still hunting a victim in 1891 [the un-named Coles] believeing that this might be the work of the same 'mad miscreant'.
Therefore, Macnaghten's 1914 version of the Whitechapel murders are diametrically opposed to Anderson's of 1910; the fiend was a Gentile, not a poor Jew, one who had never been incarcerated in an asylum, nor picked out by a Supergrass. The police did not get onto him in 1888, but years later when it was too late as he had killed himself -- because of some horror-meltdown and not a police dragnet -- after the Kelly murder.
This war of the memoirs is an upper-class, British-style Stalinism; the air-brushing out of your hated rivals and their careers.