Why has Dell stopped providing Ubuntu desktops?

I have previously ordered Dell PCs with Ubuntu pre-installed, namely the Dell Inspiron 530n. These PCs have been excellent for friends and family. Unfortunately I can no longer find the Ubuntu desktops on the Dell UK website. So I asked a Dell representative where I could find one? This was our conversation:-

Daniel Ellis Initial Question/Comment: Where have the Ubuntu desktops gone? Eg. Inspiron 530n
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System Connected with "Dell Representative"
Dell Representative Thank you for contacting Dell sales chat. This is Niharika your Sales Advisor. Please give me a moment while I review your query.
Dell Representative we do not have Ubuntu Desktops
Daniel Ellis You used to not long ago. I ordered three for various family members.
Daniel Ellis I am now looking for another one for a friend.
Dell Representative Right now, we no more manufacture them
Daniel Ellis Any reason why?
Dell Representative we now have windows 7 as OS
Daniel Ellis Is there any reason why you cant support Ubuntu?
Dell Representative as Microsoft started Windows 7, they have stopped offering Ubuntu
Daniel Ellis How does that effect Dell supplying Ubuntu?
Dell Representative when Microsoft stops supplying, Dell also does not sell them
Daniel Ellis Ubuntu is not supplied by Microsoft. It is supplied by Canonical. I dont see why Dell have stopped supplying it?
Dell Representative we are on supply constraint and its not compatible with other new upcoming systems
Daniel Ellis Sorry, I dont fully understand "supply constraint", what does that mean?
Dell Representative we no more receive Ubuntu from the respective company.
Daniel Ellis Ubuntu is a free operating system. It does not need to be supplied by Canonical. Because of the nature of the license, Dell is, and will always be free to supply Ubuntu if they so wish.
Dell Representative Dell does not supply anymore.
Dell Representative Is there anything else I can help you with ?
Daniel Ellis Is it possible to purchase an Inspiron without an operating system?
Dell Representative All systems does come with OS
Dell Representative we cannot remove them and send
Daniel Ellis If my friend doesnt agree to the EULA of the operating system. Can he remove the operating system from the computer and return all the supplied (unopened) media for a refund?
Dell Representative if he removed the operating system, we do not refund for them
Dell Representative as per Dell's policy
Daniel Ellis As I understand from reading the EULA, you have to accept the conditions of the EULA if you wish to use the operating system. What is the procedure if you dont accept the conditions of the EULA?
Dell Representative Please check Dell's terms and conditions
Dell Representative we do not refund for the operating system
Dell Representative However we do not send systems without OS as well
Dell Representative we only go according to DELL'S POLICY
Daniel Ellis Not having read Dells terms and conditions, are you able to summarise the procedure? If not please can you provide a link to the terms and conditions?
Dell Representative please log on to Dell's website.
Dell Representative www.dell.co.uk , you can find terms and conditions
Daniel Ellis I am unable to find any reference to the EULA in Dells terms and conditions. It does state that the "Customer must comply with the license conditions for any Software supplied."
Dell Representative Well Daniel,
Dell Representative We do not refund for the OS which you remove
Dell Representative This is only details we can provide you
Daniel Ellis However, it is not possible for the customer to agree to the EULA before he has read them, and so what happens if the customer does not accept the EULA?
Dell Representative We only send systems with windows 7 OS, and does not send them without OS
Daniel Ellis Thankyou, I do understand that Dell will only provide Windows 7. What I dont understand is what a customer is to do after ordering a Dell system. If the customer reads the EULA but does not accept the terms, what is the procedure?
Dell Representative we do not have any information with regards to them
Daniel Ellis It seems to me that Dell is missing this information. May I suggest that this issue be raised internally so that Dell can clearly define the procedure. Thankyou for your time this evening.
Dell Representative I will take your feedback
Daniel Ellis That is appreciated, many thanks.
Dell Representative you're welcome