I'll make it clearer.

is it not strange to even consider the legal age of consent for purely fictional characters?

No, it is not.

You seem reasonable enough, so if I seem terse or frustrated, I am not necessarily directing that toward you.

The purpose of politeness in society is to demonstrate, virtue signal even, a person's willingness to abide by the social contract. You are virtue signaling safety.

The normalization of lolicon material is not a problem because it "breaks laws," it makes it more difficult to catch warning signs from bad people early. It provides too much plausable deniability.

This is not dissimilar to the aversion of racists when they start talking about race science, or making "ironic" hitler jokes—these people are not "breaking laws" either. The purpose of treating them as socially deleterious is either to shame them into better behavior, or, failing that, to excommunicate them from society. False positives, whether these people were truly racist in their hearts, is immaterial to me—I do not care. They should have enough social sense to know better.

A disclaimer: Obviously, none of this means that I want pedophiles to fear getting help. Getting help is outside the purview of social excommunication; shame would not be serving a purpose in this case. But this fact really has nothing to do with whether I'm accepting of the endless flirtatiousness anime and other Japanese media seems to have with child sex.