Gonk, not surprisingly you're correct.
With a mono cable things changed and Motorola cable box was able to control the Outlaw, but not vice-versa.

When connecting IR out of 1070 to the one and only IR jack of the cable box, things don't work.

Looks like that jack is IR OUT only, although It's labeled simply IR.

What could I do?

I definitely need to push that Motorola out of my rack where the remote cannot "see" it...

I'm waiting on a live chat with Comcast, but I suspect I'll grow a respectable beard until I'll get an answer...