You know, "politics is the mindkiller" is not only about the conventional meaning of the word "politics". It is about tribes and belonging. Right now you are conflicted as a member of two tribes, and you may feel pressured to choose your loyalty, and protect your status in the selected tribe. Which is not a good epistemic state.

Now on the topic:

Cryonics uses up far more resources [than cancer treatment]

Do we have any specific numbers here? I think the values for "cancer treatment" would depend on the exact kind of treatment and also how long the patient survives, but I don't have an estimate.

If cryonics works, [family and friends] still suffer the same [grief].

Wrong alief. Despite saying "if cryonics works" the author in the rest of the sentence still expects that it does not. Otherwise, they would also include the happiness of family and friends after the frozen person is cured. That is what "if cryonics works" means.

Expressed this way, it is like saying (for a conventional treatment of a conventional disease) that whether doctors can or cannot cure the disease there is no difference, because either way family and friends suffer grief for having the person taken to the hospital. Yes, they do. But in one case, the person also returns from the hospital. That's the whole point of taking people to hospitals, isn't it?

trying to integrate [cryonics] better into society uses up time and resources that could have been spent on higher expectation activities

Technically, by following this argument, we also should stop curing cancer, because that money could also be used for Givewell charities and animal welfare. Suddenly, this argument does not sound so appealing. Why? I guess because cryonics is far; curing a cancer (your, or in your family) is near; and Givewell charities are also far but less so than cryonics. Removing a near suffering feels more important than removing a far suffering. That's human; but let's not pretend that we did a utilitarian calculation here, if we actually used a completely different decision procedure.

...but you already said that.

I think that this discussion is mostly a waste of time, simply because your opponent's true rejection seems to be "cryonics does not work". And then all is written under this alief. Under this alief the arguments make sense: if the cryonics does not work, of course wasting money on cryonics is stupid. But instead of saying this openly, there is a rationalization about why utilitarians should do this and shouldn't do that, by pretending that we have numbers that prove "utility(cancer cure) > utility(animal welfare) > utility(cryonics)". Also, when discussing cryonics, you are supposed to be a perfect utilitarian and willing to sacrifice your life for someone else's greater benefit, but you are allowed to make a selfish exception from perfect utilitarianism when curing your cancer.

For me, the only interesting argument was the one that a smart human in a pre-Singularity world is more useful than a smart human in a post-Singularity world, therefore curing smart people now is more useful than freezing them and curing them in future.