Buffy It is irrelevant whether he knew that or not. That the 'she' was actually he is irrelevant. The fact is (it would appear, according to reports) that he did not initiate communications of a sexual content, someone else did. Several times.
He made a grave error of judgement in responding in the way he did; it was not befitting of his position in public office and for that he needed to go. But he did not exploit any person, male or female, nor did he abuse his position of power, or male white privilege. It was a mutually consensual exchange of sexually explicate material initiated by someone else, who happened to be a 'woman' and one could only loosely argue was possibly a 'subordinate' of sorts. (although as it turns out, neither.)
Newmark had a certain reputation among younger Tory women for being, for want of a better word, a bit of a creep. Think what his position gave him access to – ambitious, younger women.
Wow. So hang on,
Are you saying it's his fault (hypothetically) that he might have had access to ambitious young women prepared to sleep with an older, lecherous creep in order to attempt to advance their career? 
Or are you saying that these 'ambitous, younger women' working in politics for crying out loud, are sufficiently stupid and naive that they would not dare spurn the sexual advances of a senior colleague? Is this 1955?
And if we turn that comment on its head, can we assume that if woman makes a formal complaint of sexual harrassment or inappropriate advances by a male colleague, we must first chat to her other male colleagues. If they say that she's a terrible flirt and a 'good time girl' who is renowned for flashing her stocking tops at the office Christmas party, then we should dismiss her claims and surmise that she has actively encouraged any sexual attention? 
As for it being 'illustrative of the struggles women face when trying to network to further their careers' well I think it would be far more illustrative if we stuck to citing actual cases of men who have made unwelcome and unsolicited sexual overtures to women in the workplace, rather than using as our example someone who er…..hasn't.
I think PeckhamPearlz* has it bang on with this:
I wouldn't disagree with the idea that a senior politician (of any gender) should be ever mindful of the power imbalance between themselves and any junior colleague or supporter and always behave appropriately - regardless of how the junior person behaves.
But I seriously take issue with the attitude that this 'appallingly immoral journalism' (to borrow from Flora) is in any way justified by the assumption that Newmark was very probably sleazy anyway.
If Sophie Whittams had been a real woman and had approached Newmark to talk about this Women2win malarky and he had (eventually) moved on to "let's discuss it over a drink ... ooh the bar's very noisy ... let's go somewhere quieter" or other typical sleazeball behaviour, then I would say, yes, absolutely - 'hang' the bastard (HtB)
But on the tangible evidence we have so far, absolutely no women were involved in this entrapment, except the ones who were used as sex objects without their consent.