> No amount of fiddling with Lisp-level `message' facilities will be
> ever able to do what you want.  I suggest to file a feature request
> (with "M-x report-emacs-bug RET") asking for a variable that could be
> bound to disable all messages, even those coming from the C level.
>
>

hi
the write-region with visit argument solved the problem!

Anyway I filled the bug report.