lens - Is it important that the Canon 1DX isn't specified to autofocus with lenses slower than f/5.6?

Seeking the lens market AND the related info WRT Canon 1D X, I found some things which seems concerning:

1st, a note from Canon's Chuck Westerfall (see here) saying:

“AF is unavailable on the EOS-1D X if the maximum aperture reported to the camera through the electronic lens mount is smaller than f/5.6. This is a lower specification than previous EOS-1 series DSLRs. [...]"

On the article linked above, it is stated that no lens have f/8 but it can be reached by using teleconverters. Ok, so far, so good.

...But having in mind the above, this means that the new Canon 1D X cannot focus on the longer (telephoto) lenses which have an aperture smaller than f/5.6, say 6.3?

This includes (at least) the following lenses:

From Sigma:

• 50-500mm F4-6.3 EX DG HSM


• 150-500mm F5-6.3 APO DG OS HSM


• 50-500mm F4.5-6.3 APO DG OS HSM


• 28-300mm F3.5-6.3 DG Macro

From Tamron:

• 28-300mm VC F/3.5-6.3 XR Di VC LD Aspherical [IF] MACRO


• 28-300mm VC F/3.5-6.3 XR Di LD Aspherical [IF] MACRO


• SP 200-500mm F/5-6.3 Di LD [IF]

...so, by buying Canon 1D X and having at least one of the above lenses and raking out the glass, one cannot use the AF anymore?