The fact of the matter is you said that "no 'progressive' talk show host ever said these things", to answer that I posted links to multiple times. And believe me there were far more than that, the woman was atrocious.
My point is, it would be nearly impossible to ever reach a point where people were "worse" than those who were against Bush. We haven't even come halfway to that point. I have yet to see people burning Obama in effigy, floats with him being beheaded, etc. (photos of which have been posted on this very site more than once, sometimes in threads you even participated in.)
No, I am unworried, if this low bar is the one you will set for anti-Obama protesters, because it would take far more than has been shown to ever get "lower" than those who attacked Bush so regularly for so many years.
Personally, I think that policy is free game regardless, and threats are horrific, however the bar you set is they'd have to be "worse"... It's nearly impossible to get "worse".
The left not only had "talk radio hosts" talking about it, movies depicting his assassination (Bush's) were played in the theaters. It's fascinating what you will decide to "remember" so that the world will fit neatly into some farcatic box you created that are the "good guys"...
Your good guys weren't so "good" during Bush's terms. Thankfully the R Party just doesn't have it in them to get as low as y'all did...

<- yes, this is the winkie, for those on the left who can't understand this is a sign that my last sentence was sarcasm. People exist that are awful in both parties, just ignoring it partisanly seems to be the only thing that is consistent.