In this case, semiconductors are a segment which Japan was leading back in the 80s. And Japanese inputs have been continuously critical for even today's leading edge semis from TSMC as well as for others like from Samsung or AMD.
So if the Japanese govt. is going to 'bet' on anything, then betting on a segment where Japanese inputs are critical, and where Japanese companies had led the world previously, is a safer bet than a segment where there is no history or inputs.