[quote=@SleepingSilence]
Sanders has yet to be lambasted over being too old, when that's the only thing, most people/the media had against John MCCain
[/quote]

That had more to do with McCains health if I recall right. He still suffers publicly known effects from the torture he endured in Vietnam, and there were rumors that his swollen thyroid meant even more serious health issues. Sanders doesn't seem to show any signs of poor health right now. There is also comparative ages to consider. Clinton is only six years younger, and Trump five years. McCain ran against Obama, who was in his late forties, so the age difference was noticeable. If Sanders becomes the Dem candidate and runs against a Rubio or a Cruz, I have no doubt age will enter the conversation. 

But here is a fun fact about ages in this election. Ronald Reagan, thus far the oldest president at election and at retirement, was 69 when he took office. McCain would have been 72 if he had took office in 2008. Sanders, if he takes office in 2016, will be 75 when he enters the white house, becoming not only the eldest president at election, but if he wins reelection and survives his presidency, he'd be the first to still be in office when he is eighty. 

But he's not the only one poised to break Records. If Trump becomes president, he would also become the oldest President ever elected, entering office at age 70. That would put him 1 year ahead of Reagan. Clinton would be just 9 months younger than Reagan was when he took office.