for src in $(find -H "$DOTFILES_ROOT" -maxdepth 2 -name '*.sym' -not -path '*.git*')
 do
   dst="$HOME/$(basename "${src%.*}")"
   link_file "$src" "$dst"
 done

For loops over find output are fragile. Use find -exec or a while read loop.

find -H "$(pwd)" -maxdepth 2 -name '*.sym' -not -path '*.git*' -exec echo {} ;

find -H "$DOTFILES_ROOT" -maxdepth 2 -type d -name '.git' -prune -o
    -type f -name '*.sym' -exec sh -c '
        link_file "$1" "$HOME/$( basename "${1%.*}" )"' sh {} ';'

find -H "$DOTFILES_ROOT" -maxdepth 2 -type d -name '.git' -prune -o
    -type f -name '*.sym' -exec sh -c '
        for src do
            dst="$HOME/$( basename "${src%.*}" )"
            link_file "$src" "$dst"
        done' sh {} +