If you have to bring a 70 year old faction leader out on major campaigns by all means do so. I just think he should have movement penalties reflecting his age, and not partake in any heavy fighting.
Somehow I just can't see a 70 year old running or riding around in the heat of battle fighting enemies with the same vigour as someone in his early twenties.
He should be ready to drop dead the moment any serious fighting reaches the bodyguards. He can still sit around looking impressive on a horse giving morale bonuses though. That isn't all that taxing.
I remember cornering a Ptoly general in the townsquare of Pselkis with four units of phalangites, two generals, four skirmishers, six Ethiopian Guard and a unit of elephants. He was alone surrounded and the elephant kept banging his sorry ass against the wall for a good five minutes, real time, before he finally bought it.
Anything to avoid that from ever happening again. Thank EB for infantry generals. Tough they may be, but atleast they don't fight their way out off a horde of spearmen, just to run off the map and come back next turn with a full stack of mercs and half their bodyguards regenerated.

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