There are, imho, three general reasons for caution in interpreting negative reaction data in the Finnish survey and in Rind's analysis of it.
First, and most important, negative reactions, especially among girls, are likely to be a product of prevailing erotophobic norms. In his 2023 paper comparing the Finnish survey with a German survey of reactions to first heterosexual coitus, Rind, citing an observation from Felson's 2019 analysis of the Finnish data, comments:
...girls, much more than boys, are sensitive to cultural norms regarding sexual (and other) behavior, and hence more likely to be biased toward less favorable reactions in a disapproving cultural-social environment....
Second, the Finnish survey, while by far the best evidence available on this topic, was itself extremely biased towards erotophobic outcomes. Its title, "Child Victim Survey," reflects this bias, confounding the distinction between children and adolescents that 16/12 relies on and conforming to the victimization narrative central to Child Sexual Abuse ideology.
Third, in an effort to ensure his results are not biased toward positive outcomes, Rind adopts a "conservative" approach to the data under which "priority in coding was given to more negative, or less positive, reactions." Note, for example, that the Finnish participants could classify their negative reactions as "very negative" or "fairly negative," a distinction Rind collapses into a single category.
With regard to the 72.6% negative reaction among girls to minor-older sex that happened when they were under 12, in addition to including cases of coerced sex, this figure also includes two other categories of experience which Rind found to produce high negatives: sex with a relative and non-contact sex.
Sex with an older relative produced an 80% negative reaction among girls. However, only 7.8% of girls with minor-older sex experiences (80 out of 1020) reported such sex. (The 16/12 proposal does not advocate abolishing the ban on incest, though it appears from the data publicly available online that much or most of the sex with relatives reported was not with caregivers.)
Non-contact minor-older sex produced a 50.3% negative reaction for girls. Rind reports that 17.6% of the minor-older experiences of girls were of this type (181 out of 1028). This category, created by Rind, combines responses to three survey questions: "What happened: Request or suggestion to do something sexual"; "What happened: The person showed his/her genitals"; and "What happened: You showed your genitals." It's questionable how much of this should be categorized as AMSC at all (to the extent the "C" stands for "contact," none of it should).
If these cases, along with coercive experiences, were removed from consideration, the percentage of negative reactions by girls to minor-older sex occurring before they were 12 would be smaller, though without reanalysis of the data it is impossible to know by how much.
As one more illustration of the caution necessary in interpreting Finnish negative reaction data, those of us who are male boylovers should note that, while the data in general supports the receptivity of boys to minor-older sex under almost any conditions, the highest negative result for boys -- 51.3% -- was when the older partner was male. We are right to at least partially discount this as representing the homophobia that remains a part of how boys are taught to understand masculinity. But we should remain alert to the many factors that should lead us to be similarly skeptical about other negative results.
None of this means the Finnish data do not support 16/12 in drawing a significant distinction between child and adolescent sex. They do. But being honest about the data should also mean being honest about the many limitations of the data.