Religious Issues
Aside from the fact that Florida has no statute of religious objection to autopsy, I think that religious objections will be weak grounds to prevent autopsy.
In both Islam and Judaism burial of the body as soon as possible might be used as an argument insofar as autopsy could prevent speedy burial. Moreover, both religions prohibit disfigurement of the human body as being a disfigurement of the "image of God". Nonetheless, autopsy is being used increasingly in Muslim countries:
Forensic autopsy practice in the Middle East: comparisons with the West
in accordance with "fatwas" by religious authorities supporting the service of Justice.
In Judaism, it is only the Orthodox Jews that object to autopsy, not Conservative or Reform Jews:
Autopsy: Traditional Jewish laws and customs
But even the Orthodox Jews would not object to autopsy in the case of suicide, insofar as a Jew who has committed suicide is not even deserving of a religious burial. Autopsy for the purpose of determining "suspected suicide" is a murkier question.
Many Christians give lip-service to the Apostles' Creed, the next-to-the-last line of which refers to the "resurrection of the body":
Wikipedia entry on "Apostles' Creed"
But most Christians probably agree with the Apostle Paul that this is in reference to the non-physical "spiritual body":
Wikipedia entry on "Spiritual Body"
Most Christians believe that their spirit will go to heaven and have no concern about their physical body.
There have been a few Muslims who have been cryonically preserved, and possibly even Orthodox Jews, but these would be rare cases, and should not be the focus of our attention. We are most concerned about unobserved deaths and, to a lesser extent, homicides, rather than suicides (except for "suspected suicides"), but in all cases I think we should concentrate our efforts on trying to prevent invasive autopsy of the brain, arguing for blood samples and imaging methods.
Scientific Issues
Bill Faloon has expressed concern about a NEW ENGLAND JOURNAL OF MEDICINE article arguing in favor of autopsy:
Case 23-2020: A 76-Year-Old Woman Who Died from Covid-19
Bill Faloon has emphasized the following statement at the beginning of the "Role of Autopsy" section:
Even in an era with routine use of high-resolution imaging, published studies have shown that approximately 50% of autopsies reveal findings that were not suspected before death and 20% of autopsies lead to the diagnosis of a primary cause of death that was not established clinically. In the absence of an autopsy, the likelihood that a death certificate will be inaccurate is at least one in three.
The reference to "high-resolution imaging" is in connection with imaging for clinical pre-mortem diagnosis, not in reference to forensic imaging. The article argues that autopsy is of value not only as a means of determining cause of death, but as a scientific tool to understand the pathology of COVID-19. There should be many patients available for COVID-19 studies, without having to use cryonics patients. The article does not argue that a non-invasive imaging autopsy is inferior to an invasive autopsy. No such distinction is made, only the word "autopsy" is used. The authors do express some sensitivity to the family's emotional state.
Forensic imaging provides graphic documentation of an autopsy, which manual autopsy does not. CT (Computed Tomography) scanning provides quick whole-body imaging of skeletal and parenchymal alterations, whereas MR (Magnetic Resonance) imaging gives better representation of soft tissue pathology. But MR is more expensive, and more time-consuming to utilize:
A Practical Guide to Virtual Autopsy: Why, When and How
Moreover, the quality of MR imaging deteriorates below 10°C:
Essentials of forensic post-mortem MR imaging in adults
— and we should hope that bodies being held for forensic evaluation would be below 10°C. Additionally, a 2013 survey of forensic radiologists indicated only 5% were familiar with MR compared to 55% with CT (see reference just cited).
I believe that our arguments against invasive autopsy should emphasize scientific and legal issues rather than religious ones. Florida has no statute on religious objection to autopsy. Legally, the Uniform Anatomical Gift Act (UAGA) should be our strongest tool. Page 481 of the article Whose brain is it anyway? The comparative law of post-mortem organ retention indicates the use of UAGA in Florida statutes to restrain the hand of a medical examiner — although the reference is only to corneas (765.5185 Corneal removal by medical examiners) and only to objections by next-of-kin, rather than by the deceased. Nonetheless, I believe that UAGA can be used in Florida to protect a cryonics patient:
Florida statute law supports donee right to be cryonically preserved