All E-Business Suite Application binaries are 32-bit. The only exception are ASCP Memory Based Snapshot programs: MSCNWS64.exe and MSONWS64.exe. These are 64-bit binaries. They have been made 64-bit because of their memory intensive nature.
I noticed that whenever we run adadmin to relink binaries of MSC and MSO, these two are never relinked. If you try to relink them manually through adrelink.sh force=y "MSC MSCNWS64.exe" it simply deletes the file and doesn't relink. I asked Oracle about this in an SR and this was their answer:
How to relink MSCNWS64.exe and MSONWS64.exe manually and through adadmin ? We have seen that these files are not relinked if we relink all MSC and MSO binaries through adadmin
Recompiling the 64 bit Memory based planner executables that you are asking about is not required and doesn't work as the code lines are all self contained within that executable and it doesn't use other files in other directories like other executables for recompiling. So basically if an install or patch is applied this executable is fully self contained in similar fashion as if you were running a Netscape browser which is also an executable netscape.exe - so these executables do not need to be compiled/recompiled.