I agree with both of the above comments and the question. Did they offer to do it for you or have a dealer do it? It sounds like their reason was valid for their protection and the protection of their customers.
Mcintosh customer support
Requested Firmware update from Mcintosh for my ageing but still good sounding D150 Dac Mcintosh customer support virtually refused to supply Firmware v 1.02 with me . their answer was,,
( Unfortunately, company policy prohibits me from sending out firmware updates. We used to distribute them openly but they ended up on forums and were installed into incorrect units causing a massive influx in service repairs. At that point the company instituted the policy to no longer distribute them.)
it is so sad that Audio Giant like McIntosh do not care about their customers.