It is not that the n9 does not supprot IrMC. It is just that pbap is enabled (--pbap) while irmc is not (there is no --irmc commandline option in your ps output) Adding --irmc should enable IrMC.

As for copying obexd, please first renamen the original obexd so you can easily switch back.
The libopenobexd can be placed in /usr/lib/ Note also the symlinks for libopenobex (see 'ls -l /usr/lib/libopenobex*' )
I guess there is also an libopenobex on the n9 but may be packaged with the obexd package. So please check before copying the n900 one and rename before copying.

You also might try using the libopenobex on the n9 (if it is there) if it is the same major version (e.g. libopenobex.so.2.x)