I have consulted our developers and got the following explanations:
"Tester leverages an API in order to get the HTTP details (for example: the real headers sent by Chrome, the details of the response, etc.). In the case Tester is asked to not follow redirect response, this API does not get any details about the response body.
So we've chosen to display a message explaining why.
We are still able to gather the response's headers and display them."