rst2man does not escape '.' at the start of the line. As a result, if the world ".hello" is located at the start of the line, rst2man just copies the word unescaped and man(1) treats it as a macro and finally the word disappears.
$ cat bug.rst
$ rst2man < bug.rst > bug.1
$ cat bug.1
.TH TITLE "" "" ""
.\" Man page generated from reStructeredText.
.\" Generated by docutils manpage writer.
$ # See .hello is copied verbatim.
$ man -l bug.1
$ # See .hello disappeared.
Version: docutils 0.8.1-6 Debian