I'm talking about the parts these yellow arrows point to. I would put money on them being plastic.
ABS doesn't melt or deform under temperatures below 220F. It would be perfectly acceptable in that position under the air intake box. Every car I have ever owned had an ABS plastic intake manifold that bolted directly to the head, just above or next to the engine block.
On the F1 engine they have the benefit of being elevated quite far from the major areas of heat with the true throttle body inlets below them as a buffer from the engine.
>8^)
ER