It's not a technical issue, it's incompetence.

I bet it was an AJAX based form, and I bet it was created using some mickeysoft (s)tool.

I mean, come on... to resolve it you don't need to remove the whole form, you need to either: make it send it's requests to a secure server; or remove the validation system for now (replacing with javascript if appropriate as time allows).

Oh well, another one bites the dust!