You are not casting an int to a bool (which would indeed do the right thing) but casting a pointer to int to a pointer to bool which violates strict aliasing.
In this case the expression has type bool and the underlying object has type int, so it is a straightforward strict aliasing violation.
With GCC you can compile with -fno-strict-aliasing to ignore this rule. But now you fall afoul of the rule that prevents accessing an invalid representation (i.e. a trap-representation) of an object. This rule is also described in the link I posted before, under the object representation paragraph.
Even ignoring both rules, there is still no reason to expect the assertion not to fire:
int x = 2;
assert(*(bool*)x == true);
float x = 2.0
assert(*(int*)x == 2);