Cisco Firewall :: ASA 60 Minute Inactivity Timeout?

We had an issue the other day where doing backups through the firewall (don't ask) caused the "control" session to timeout while the backups were still going on over the "data" connection.  This broke the backup about two hours into the job.  My first thought was that the backup solution vendor should implement some kind of tcp keepalive for the control connection.  A packet capture showed they indeed were --  after 2 hours!  Ah ha!  Busted!  How could they choose such a poor choice of TCP keepalive timer for their application that would not be compatible with the 60 minute inactivity timer that so many firewall vendors use (Cisco, Juniper, Checkpoint and Fortinet all use a default 60 minute inactivity timer for TCP)?
 
Well, a colleague of mine pointed out that there is actually an old RFC that covers this.  RFC 1122.  It says:
 
Keep-alive packets MUST only be sent  when no data or acknowledgement packets have been received for the  connection within an interval.  This interval MUST be configurable and  MUST default to no less than two hours.
 
Now I know that RFC is old (October 1989), but that's all I could find.  Is there something that supercedes that?  Maybe common sense perhaps?  I understand not wanting to fill up your connection table because of mis-behaving applications, but I'm just looking for ammunition to use against the backup solution vendor.  Surely they're going to point to this RFC.

ASA(config)# timeout conn ?
 
configure mode commands/options:

  0:0:0 | <0:5:0> - <1193:0:0>  Idle time after which a TCP connection state
will be closed, default is 1:00:00
  <0-0>  Specify this value to never time out