>"just" a theory makes no sense

Sure it does. A theory that has little explanatory power due to the lack of available evidence can, in the diminutive sense of "just", be called "just a theory" where the understood context is comparative to a theory with a high level of explanatory power and perhaps a general consensus among experts in the field.

Even something that's just a theory is not to be confused with "mere" conjecture, and somewhere way down in the hierarchy have "pure poppycock". Though even pure poppycock on occasion rises up through the ranks, much to the embarrassment (often post-mortem) of those who pooh-poohed it previously. Of course "pooh-poohed" is not a generally accepted scientific term, I use it here as a mere colloquialism. I'm sure (though not certain) that people already understand that and wouldn't bother being pedantic about it.

> I'm sure (though not certain) that people already understand that and wouldn't bother being pedantic about it.

It doesn't make sense to use it this way given the context of the discussion, though, that's my point.