I had the same issue with the esxi version "vsim_esx-7m.tgz" of the 7-Mode VSIM. The workaround I used was from the workstation version "vsim_netapp-7m.tgz".
Take the workstation version (I have Fusion on my Mac)
1) open and run the vmx file from the extracted "vsim_netapp-7m.tgz"
2) ctrl-c to break the boot to the loader
3) power off the VM
4) once powered off, file --> export to OVF
5) in ESXi, import the OVF
If you need more 7-Mode images, just repeat step 5... then follow the instructions as needed to set the serial number SYS_SERIAL_NUM, bootarg.init.nvram.sysid and option 4..
For the cDOT image, I had no issue with the esx image, only 7-Mode.