A heat pipe is not necessarily containing a liquid for phase change. However, ignoring for the moment whether or not this particular pipe has a coolant in it, consider the following…
Phase change liquids tend to require convection to send the gas phase upward, and the liquid phase downwards (and is the basis as to why the original question matters). Check the default orientation of the dev kit sitting on a desktop:
This image shows the copper tubes are all parallel when placed on a flat table, and do not have the possibility of vapor and liquid being useful even if the pipes contain this medium.
Now if we were to orient the module in any other direction, then the liquid portion would never cover the contact point with the module. Only gas phase would exist there, and the liquid would be elsewhere (which would be the reverse of useful).
As thin as that pipe is I believe this was only used as an ordinary copper heat sink since it is easy to manufacture using tube. The ends of the tube don’t even appear to be hermetically sealed. This solution should not care about orientation, but if it does have liquid content for phase change, then there was a mistake in the design. The design is incompatible with liquid phase change.