MINIX 3 security?

although it seems that the highest advised form of security is whonix+qubes or whonix+physical isolation, would a system with minix 3 as the host os and physical isolation between two whonix-running machines be even more secure?

this setup would seem to be even more secure than qubes, since the minix kernel only contains ~6000 LOC, versus Xen’s >150,000. Combined with physical isolation, it would appear that this setup would be the most secure. What are your opinions on the matter?