You know you're full of shit when your best defense over an attack that clearly crossed a line is to dredge up another supposedly similar attack from your arch nemesis. And it's even lamer when the comparison you're citing is vague at best and totally nonexistent at worst.
There's no doubt that Donald Trump was mocking New York Times reporter Serge Kovaleski's disability during a campaign stop. Any reasonably intelligent person who looked at the video would conclude the same. But rather than apologize for the incident, which seems to be anathema for Trump, his campaign has instead decided to deflect attention away from his malfeasance towards an ad that Barack Obama ran against John McCain in '08.
The Obama ad did indeed poke fun at the GOP nominee, but it went after what many people felt was McCain's inability to keep up with current things from computers to the economy. Obama was trying to draw a distinction between someone who was in touch with the latest trends and someone who clearly wasn't. I've watched the ad several times and I cannot see any evidence that it crossed a line by making fun of McCain's disability. In deed, a google search revealed two striking things: 1. the only objections to the ad came from conservative sites; and 2. there is nothing from McCain himself indicating he found the ad offensive. Ironically, it was Joe Biden who came to McCain's defense, I suspect because the ad's overall theme was that older people weren't as capable as younger ones and Biden was closer to McCain's age than Obama's.
At any rate, the two are not even remotely equivalent. On the one hand, you have Trump on a stage doing a mock interpretation of a man with a disability right down to the hand gesture; one the other, you have a campaign ad that was clearly drawing a distinction between a young, viral man who represented today's generation and an older, more feeble, out of touch man who represented the past. Was it a nice ad? No, but then most attack ads aren't. That's why they're called attack ads. But the ad did NOT go after McCain's disability and there is no evidence that has been presented by "credible" sources that proves otherwise.
Once more another false equivalence argument has been made by the GOP in an attempt to distract people away from the real truth. Since he announced he was running for president, Donald Trump has made numerous obnoxious and disgusting comments about Mexicans, women, Muslims, and now, the disabled. To add insult to injury, Trump has demanded an apology from The New York Times, I suppose for having the temerity for condemning his remarks. In case you haven't been following closely, he tends to do that a lot with any newspaper that calls him out. There seems no limit to how low he will go to garner support from a base that is racist, myopic and nativist. That the Republican Party would not condemn his outlandish conduct and instead dredge up a seven year-old ad is pitiful and, sadly, indicative of the state it now finds itself in.
Think about it, Donald Trump might well become the Republican nominee for president. If that should happen, you will see the entire party apparatus go to bat to defend a man who represents the very worst in our country. And that fact should scare the living shit out of you.