As expected, here's BMC's response:
Thank you for yourinquiry. Using your carbon BMC bicycle on a trainer with a fixed axle goesagainst our Carbon Care instructions (http://www.bmc-switzerland.com/us-en/support/carbon-care/).Having the axle fixed in placed can put excessive loads on the dropouts andultimately cause damage to the frame.
Best regards,
BMC SWITZERLAND – CustomerService USA