I don't deny the physical assault charges that follows as I remember years ago a trans sexual was murdered and the perpetrator argued that his reaction was normal for any homophobic male. He was still convicted.
Re: And I don't think it's sexual assault either. If a tgirl asks a guy if he wants a blow job and he says OK, it's consented to. End of story.
Interesting that a consent from a tgirl misrepresenting herself isn't assault but consensual sex where a condom is slipped off is assault. (the later of which I do agree).
So let's expand your 5 minute BJ quickie to a tgirl advertising as a female on a dating site and actively sustaining that lie into the eventual and inevitable conclusion in the bedroom. Obviously the victim of this charade is in for the same level of shock as a girl who finds out her consensual sexual encounter has a surprise she wasn't counting on. I maintain the same selfish interest of sexual gratification at the victims expense is present in both cases.
I suggest that the current laws are not a measure of right or wrong. There were laws that allowed burning witches, segregating blacks and currently (thanks Harper) make it an offense for grown adults to negotiate sexual favours.
You either consent or you don't.
The law does not make a distinction that the end result meets your expectations. I.e. if you consent to a receiving a blow job and the other person consents to giving it, but you as a heterosexual male expected that blowjob to be given by a woman. I don't think a man should be able to say, "I consented to receiving a blow job from what I thought was a woman and it turned out to be man" and be able to press charges. Get over it and move on. You asked for and received a blow job from a willing participant you came, so be it.
I understand your "yeah, but" argument about a guy slipping off a condom, or poking a hole in a condom to get a woman pregnant, or slipping a finger up an asshole when it was not desired, or cumming in a mouth unannounced. Is that sexual assault? In my opinion, no it is not. Consent was given to engage in sexual interaction. That consent carries certain risks and I believe that people need to accept the risk that comes with sexual interaction. Be that an unplanned pregnancy, a cum shot where you didn't want it, or a finger in the asshole. You'll live. There is simply not enough time and resources to deal with everyone who has regrets and feels victimized. The way things are going, you're going to need a written contract about an inch thick spelling out the terms of the sex so that all parties are liable. Sounds absurd, but....
I'm not saying that deception is cool. I don't like people who do things they were specifically told not to do. I'm saying that that's a risk you take.
Some may call this blaming the victim, but I call it taking responsibility for your own actions. But here's the funny thing, you will get over blaming yourself far easier and far quicker than you will thinking of yourself as a victim and blaming someone else.