Per CIMMS, half the LL vorticity is over land. Plus the N shear, almost 30 knots. I think Dr. Cowan is right, won't do much next 2-3 days. He also suggested, because of the shear, if the system somehow strengthens, it will tend to stay further S next 3 days. Or stronger is farther S, not the usual stronger storms go N and E.
The 70% 2 day should be reduced, but I can see how NHC would think that is sending a mixed message on what probably is a US threat.