My (1) and (2) I had hoped to be an obvious either/or branch

So, yes:

1. @TenantDiscriminatorColumn (or {{@TenantDiscriminatorColumn(parameterized=true) - the default) -> (parameter) Grab the AST, generate the PreparedStatement, bind the param value and execute
2. {{@TenantDiscriminatorColumn(parameterized=false) -> (literal) Grab the AST, "clone" it, add the discriminator node and execute