his remaining base is consistently 10 percent Democrat, 25 percent Republican, and 65 percent independent

Previous polls showed him drawing much more evenly, but ok, for sake of argument let's assume this is correct. A major reason for Johnson drawing fewer Democrats could be that Democrats opposed to Clinton and Trump may be more likely to vote for Jill Stein over any of them. So then:

If you add 10 percent of Johnson's totals to Clinton, and 25 percent to Trump...

This is a totally bogus and unwarranted assumption. It assumes that the independents who support Johnson would otherwise vote for Trump, and absolutely no evidence or reasoning is presented to support that. It could make more sense to split the independents evenly, so 42% go to Clinton and 58% go to Trump. If you then take Jill Stein's votes and give them to Hillary, you get back to about 50-50.

So no, yet another alarmist and ill-informed piece trying to fear-monger folks from voting for what's clearly the best ticket in the race.