The scary thing is I don't think I'm being very sarcastic. Now I have a much clearer reason why I need to suck it up and implement a typechecker for real, and deal with the unknown hard problem of typechecking BI-like typesystems.
(*from the point of view of a certain external sort of notion of soundness --- I implemented a bunch of little carefully restricted combinators, started writing some code in terms of them, and then realized that one of the combinators irrevocably violates the intended contract of the combinator library, and I pretty much can't do without it)