By using a bareword, the author of the previous code is effectively using a package variable to store the filehandle.

Hmmmm.... This does not directly relate to my question as about whether or not Perl closes the local file handle properly at the end of the block, but as to the risks of bareword file handles, I think the only risk would be if I call in my block a function, which in turn would use a non-localized filehandle of the same name.

The file handle I as using, certainly can not close another open file handle of the same name, because it is localized.