I think she means she would have struck her son had he done something similar to the other prince.. The translation a d proof reading on this is a bit whacky.
The shitty development aside how is this guy so short when his sister is that tall. Clearly, he has the genes for a good height. Was he mal nourished as a kid that inhibited his growth??
The double timeskip was a bit weird, but at least the series became a better class of garbage than it was during that whole searching for his psycho sister arc.