Why install an old version? I would start by trying ESXi 5.1. The updated drivers may well be all you need to fix it.
The answer to your question though is that the point of the HCL is the response you get from VMware if you go through official support channels. Assuming you have a support agreement, they should get on this and work on a fix. If you don't have a support agreement, well, you can't complain about free support.
Edit; I checked the HCL and now I can see why - the server is too old support ESXi 5.1.
Also according to the HCL, this server only works with ESX, meaning it's not actually as certified as you think. You could probably confirm this as an issue with explicitly unsupported hardware.
Message was edited by: Josh26