To clarify, men and women wearing whatever, AOK.
The galling bit here is the insistence that wearing whatever you like to work:
A) must mean something, and automatically be a positive benefit to other people. IME- neither. I find it offensive that my male bodied colleague feels it professional to wear skimpy party clothes to our workplace and HR sees that as fine, given none of us women have that choice- so I think they’re insulting women. I find it scary and demeaning of my own privacy and dignity and that of my female colleagues, and highlighting of our female lack of power and respect at work, that I have to share my unadapted, female toliets at work with male-bodied colleagues just because they wear female clothes, wigs and make up.
b) breaks down gender stereotypes which is laughable when it’s entirely premised on them- ‘I’ve got more heels than my wife and daughter!’
c) somehow means P is ‘non-binary’ while enforcing a binary of stereotypes
c) that wearing a lot of make up, a wig and pink dresses to work makes P a woman 
d) somehow Pbgets to evade the screamingly obvious point that in the professional arena they is in, no woman could survive for 5 seconds if they ‘womaned’ in the way Pippa does. So Pippa’s rubbing their partywear in their faces as a blatant bit of power-play about all the ‘expression’ choices that they will never have if they want to be at senior level like Pippa or Phil. They must conform and wear female-coded drabs, P can do whatever he likes! And be feted for it!
E) that everyone else at work has to validate and be bit players in what would appear to be P’s AGP which is a sexual fetish, (i’m going to assume because Pippa is frequently referred to as a woman that Pippa gets to use the women’s toilets at her office. Funnily enough in this super enlightened inclusive workplace the toilet and changing room arrangements for women are not mentioned. That makes me a bit suspicious as to whether women make up 50% of the senior level workforce or if they feel they have an equal say in trivial things like eg their own toilet arrangements at work)
F) that P is co-opting the language of gay liberation, ie ‘come out’ which is a completely different struggle that he is not part of and is not contributing to
G) that he has so fucking little sense of irony (or acknowledgement of his own white, male, monied, SAHM-supported privilege) that he says it’s a ‘travesty’ (look up what that word means in the dictionary!!) for others not to be able to come out ‘as a [ed’s note- insert: ‘male sex fantasy stereotype version of a’] ‘woman’ in the workplace just like he has.
www.google.co.uk/search?q=travesty&ie=UTF-8&oe=UTF-8&hl=en-gb&client=safari
In fact while they are at it- they look up what ‘woman’ actually means. Spoiler alert: It isn’t determined by what clothes you wear, sorry.
BTW if they is so enlightened and into diversity and inclusion they really should know that ‘TERF’ as a sexist term of abuse and never use it.
Furthermore they should know its no one else’s job to be happy for them (especially for taking a woman’s award, by virtue of wearing woman’s clothes...) and he must know that it comes over really narcissistic when he’s angry-tweeting sexist abuse because he’s not getting more praise?