I have never seen a grease nipple on the timing chain case.
Anything there is indeed a modification.
The engine is designed to leak some oil past the timing pinion and to drain any excess through the pipe at the bottom.
I guess both grease or oil will do but grease is not necessary on a "normal" engine.
If you put in grease I guess it will have to be a lot!
As mentioned before it may melt while hot and clog up the drain as it cools.
Whether that is a problem, I do not think so.
The grease will however be diluted by the oil which will come from the pinion anyway unless that passage has been blocked by a deliberate seal.
I do wonder if that is the case.
