Confusion on servers where HEAD method not allowed

I have discovered to my surprise that some servers don't allow HEAD requests (e.g. pages-custom-15.weebly.com URL http://www.getdowndog.co.uk). This can be verified by connecting with the Unix utility nc or "wget --spider http://www.getdowndog.co.uk" which report "405 Method Not Allowed". This also confirms it's not related to the user agent string.

Actual behaviour:
This module reports a broken link with "-1 request timed out". Unfortunately that seems to be the behaviour of the underlying function drupal_http_request. The HTTPRL version of the function behaves similarly.

Expected behaviour:
Ideally retry with a GET request, and detect a working link. Otherwise perhaps a more accurate error message? Or if not, perhaps document this as a known limitation?

linkchecker version 7.x-1.2
core version 7.31

I can see that your answer may well be that the bug is in core - and I won't argue with that. However I thought it was worth raising in case you are able to fix it, and if not, at least it brings it to your attention.