It seems like a totally natural thing that someone would say, and they would say it with a distinct pause after 'rubber'.
No, it really doesn't.
This was a difficult question to research. I tried searches and got dozens of sites explaining the "natural order" of adjective, but none I looked at went on to describe what to do when the author specifically wants a different word order.
I sent questions to some of the sites returned from my searches. The first to reply was Paul Shoebottom from the Frankfurt International School (fis.edu).
This is his reply (with some font changes I made):
Adjectives preceding nouns can be coordinate or non-coordinate. Coordinate adjectives are adjectives that could be joined by and. They are normally separated by commas. Example:
It was a long, loud, tense meeting (We could also say the meeting was long and loud and tense).
Conversely, non-coordinate adjectives (particularly those of shape, color, size, material that describe physical objects) are generally not separated by commas. Example:
a long black dress
a big red rubber ball
We would not normally say: The ball was big and red and rubber.
So much for the theory. In practice of course, it is not always easy to determine if the adjectives should be considered coordinate or non-coordinate.
In the present context, (non-coordinate adjectives) where you have good reasons for subverting the normal adjective order, then the comma seems to be an appropriate device. The Right Word at the Right Time has this to say on page 146:
Some types of adjectives have relatively fixed positions in relation to one another. Sequences of such adjectives need not have commas:
a round red ball.
This sequence exhibits the typical order, in English, of adjectives of shape before adjectives of colour. When such adjectives occur out of order, however, commas are more likely:
a red, round ball
So, I think your objectors are wrong in this case.
You are welcome to contact me via the SOL mail system if you would like me to forward copies to you of the emails we exchanged.