Earlier quoted context omitted.
Indeed, I think it's a terrible mistake to hold historical figures to modern standards and morals. I'm sure there are things even the best among us do today that could be harshly judged in the future. "Of this I am quite sure, that if we open a quarrel between the past and the present, we shall find that we have lost the future" -- Winston Churchill
Some morals aren't as modern as people make them out to be when making this argument. Also interesting to use a quote from a man responsible for starving millions of innocents in a debate about morality, but that's neither here nor there.
Not people? I'd hate to be referred to as 'an innocent'.
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To address the main point, history is full of this. I mean, try quoting Mother Theresa and see what people will say then.
We _could_ try to cleanse history of all memorable quotes written or spoken by people who have don't have a clean track record in morality (whatever that actually is at a certain point in time) but I don't think we'd be left with all too much to learn from.
To go further into my own thought process, I'm much more in line with non-dual tantric attitudes to this than I am with what we commonly call morals these days.