You can do it.
Should you do it, I cannot answer.
The TC does not need partitioning.. indeed cannot as you say be partitioned.
The Mac will create its own special virtual disk, called sparsebundle. That will keep it isolated from PC backup.
For PC simply create a new directory under the main data directory.. call it something obvious. PCbackup, and use that for backup software you use.
Here is my TC.. it has my MBP laptop backup sparsebundle.. and my wife's PC backup.. suitably named.
Bad things happen when the drive gets near full so make sure it never even gets close.
There is some warnings here you should know beforehand.
One very good idea there is to set a max size for the sparsebundle.. say you have a 2TB disk TC.. set the sparsebundle to 1TB.. as soon as you do the first backup as that will reserve the space for it.
Never tried but I will have a go..