The dealer will make a hand quite often with a "deuce" showing. As a matter of fact, the dealer will make a hand of "21" more often with a deuce than with any other upcard. Certainly, the deuce is still worse for the dealer than the 7 or higher, which can be "made" hands right off the bat, but not by a whole lot.
There is only one card she can have in the hole that will give her an instant "bust" scenario, that being the ten. Even then, she must draw another ten to bust.