Could be. The scare was that the anti-UNIX folks would get wind of it and it would used in the fight as to why VMS was 'better.' The CS Research community has not yet made the switch off the 36 bit world to Vaxen, so the Arpanet community is still pretty much PDP-10 central; but it was also right around the time when DARPA was defunding the PDP-10; had chosen the VAX but was arguing VMS vs UNIX.
I don't thing CSRG had been funded as a group yet. Joy might have done his 'fast vax' paper to show that UNIX was just as good as VMS, but that work might be on the horizon. Certainly all of 4.1a/b/c, 4.2, 4.3, NET-x was years away.
The point is that you didn't (yet) have a mass of students on the systems 'in the field', but some folks had that as a vision (and want it to be that way and are scared it something bad happens 'in the press' - it would cause a set back.
At the that time, think a couple of Universities are >>starting<< to use UNIX for general CS classes/teaching (Purdue & UCB being two of them), maybe Michigan and U of I, but I think CMU and Stanford are still using PDP-20's [not sure about MIT] (where Princeton and UCLA I think were still IBM shops for undergrads).
So the whole reason to keep it quiet @ the USENOX conference was because it was felt at the time, the folks in that room were the primary people hacking the kernel and if we all took the couple of lines of fix back to our shops, the problem was solved.
It sort of blows my mind if Doug never knew about it, in hind sight it seems George got his wish!!
Clem