I get where you're coming from, but in my experience at least "toxic masculinity"/"masculinity threat" just pushes people into more self-hating and reactionary or extremist beliefs.
And to me it seems analogous to "preying on their racism for good"... by making racist insults... rather not?

Hasan was not even making any coherent argument:
Diversity of physical traits exists within binary categories of sexual dimorphism, therefore be more open minded about gender expression.
This type of non-sequitur is something Shapiro's audience are practically trained to recognize.

The piece missing in Hasan's argument is something like "intersex of the brain" but he doesn't want to go there.
And reality is unfortunately not that simple either.

Or reading it differently: Shapiro insults people for their "choices", while Hasan was insulting for physical traits outside of their control.

This is why most left-liberals are worthless allies: they are all about accepting everything (including abuse, ableism, imperialism, etc) but fail to understand or explain much of anything.
And that is by design. If people have stronger beliefs that are grounded in actually understanding things they become much harder to manipulate via propaganda.

Again, the most productive course of argument, in our opinion, is specifically to undermine "masculinity threat", to alleviate rather than reinforce their self-hatred; i.e. gender is false dichotomy, femininity as weakness is misogyny.
Far too many reactionaries use right-wing, cisheteropatriarchal, and White supremacist beliefs as a kind of salve to alleviate pain and anxiety; such ideologies are like delusions of grandeur, a defense mechanism, aka copium.
To remove the belief, first remove what makes it necessary to them. Motivated reasoning can be nearly impossible to contend with; to the point where people can even dissociate/repress things.

Also being tiny and cute doesn't mean you're weak; and specifically doesn't mean you're weak in that sense that Shapiro was referring to.
Society does not need "strong men to carry the heavy things", we have cranes and machines for that; Shapiro means strength in the gender identity sense of being willing to take on confrontation, moral courage, resilience, that kind of shit.
Worth noting that recent Chinese propaganda specifically focuses on clarifying things like "femboys are not weak in the moral sense".

Because that is the sense of masculinity (as social role that boys are taught) that Shapiro operates with, insults about his appearance land nowhere near it.
Even if Shapiro's followers were hurt, they simply reinforce their socially-constructed toxic masculinity (that defines itself largely in opposition to femininity) and become more callous to compensate for their supposed insufficiency.

In fact, this is how the /r/StupidPol-sausage gets made; they specifically construe LGBTQ people as mentally ill and morally weak which is evidenced by over-sensitivity about misogyny/ableism/body-shaming.
To to quote fashy troll cuckfucker93: "pussy whining about decorum like a lib"

In addition to that, much of transphobia/queerphobia is rooted in disgust based intuitive thinking; many reactionaries specifically moralize about LGBTQ issues, which is all bound up in disgust circuity.
It is the opposite of helpful to reinforce/reactivate these kinds of (subconscious) networks by associating appearance and femininity with insults and aversion.
Again the analogy of "preying on their racism for good" is applicable.

Emasculation is always reactionary. :gui-better:

Hasan's approach to Shapiro makes it look like he doesn't know anything about how reactionaries think at all.