Could wordpress “bring down” a whole server?

Apparently the company that hosts our website hates wordpress. This is an email communication that happened yesterday. Is he over reacting?

Hey ****,

I am attempting to point a wordpress installation to
yellowfinindustries.com/blog/. I have the MySQL database set up on a
different host and it is pointing to http://www.yellowfinindustries.com/blog/.

I get this error:

Directory Listing Denied
This Virtual Directory does not allow contents to be listed.

You can see the error by going to the page. This is because IIS has not
been configured to look for a default document called “index.php”.
__

To fix:

1. Go into IIS admin
2. Right click on the root dir where “blog” resides
3. Select the Documents tab
4. Click on Add…
5. Enter index.php and click OK.

That is how I have fixed the issue in the past, but it has been at least a
year since I have opened IIS, so it might be a little different. Ideally I
need “index.php” to be listed under “Directory Indexes”.

Thanks!

This is what he sent back

Adding a new default doc to the server config won’t work; we don’t allow PHP to run
on IIS. The web server won’t know how to process the scripts.

My recommendation, if you need a PHP server or application, is to install and
configure it on an external server and link to the appropriate pages from your
static content pages.

In the future, please consult with me before installing any scripting on our server.
In IIS 6, it is possible to crash the entire web server with mis-configured scripts,
and that would bring down all of our sites simultaneously, which is incredibly
expensive to diagnose and recover from.

Is he just giving us the run around, or is that pretty legit?