Tested beginning with Lubuntu 14.04.2 i386 and the HWE EOL upgrade boots fine.
Also fresh installs of Ubuntu GNOME 14.04.5 work perfectly well on the same hardware. I even applied all available updates to a freshly installed 14.04.5 and it still boots just fine.
So, based on current results, this is somehow limited only to HWE EOL upgrades on Ubuntu GNOME.
Tested beginning with Lubuntu 14.04.2 i386 and the HWE EOL upgrade boots fine.
Also fresh installs of Ubuntu GNOME 14.04.5 work perfectly well on the same hardware. I even applied all available updates to a freshly installed 14.04.5 and it still boots just fine.
So, based on current results, this is somehow limited only to HWE EOL upgrades on Ubuntu GNOME.