It wouldn’t have the goofy shape. All the dev kits were horizontal. No one blows heat down, every cooling system draws lower cooler air and shoots it high. It’s antithetical to basic facts about heat
Convection does happen, but the various applications for various consoles shows a limited regard for it when it comes to active cooling.
Sony seems to generally rely on blowers versus Microsoft's axial, but discounting the more unconventional layout of the Series X, it seems they generally are agnostic about which way warm air rises.
Axial fans blowing into a heatsink forces air in all directions, so air tends to go anywhere but up.
At least with the PS4 and perhaps the PS3, the blower direction seemed more concerned with getting the chips and the power supply, which was mostly perpendicular to slightly angled upward in the vertical axis.
The PS5's PSU looks to be on the lower end if standing vertically, so the overall direction seems to be align with that.
I'm not an expert on warm air convection or fanless enclosures, but the air flow created by convection is very modest. It's far below what fans are capable of and very insufficient for this class of device, and they tend to be more tightly packed with components in the way of convective flow.
Allegedly it also idles ten degrees hotter than XSX. All of this would explain a lot if it turns out to be accurate.
Unverified at this time, but also not necessarily a sign of overheating, particularly at idle. Idle temp can also be a choice, perhaps a tradeoff for noise or fan curve behavior. None of the temps seem out of line with routine PC idle temps.