I'm glad these two are trying to get more kids into engineering (female or not), but their thesis is pretty hollow on a few fronts. Most importantly that engineering toys lead to engineering kids. But also that engineering toys that currently exist (lego/knex) have some kind of implicit feature that keeps them out of the hands of girls.
[1] http://content.time.com/time/health/article/0,8599,1650352,0...