He can but surely later kena ban by his government

Yes he did and he hate it so much.He even publicly critize Abe(Japan PM) for his denial of Japan ww2 atrocities.

Miyazaki touches on his childhood memories of surviving the war and witnessing its aftermath. Upon learning what the Imperial Japanese Army had done in China, he wrote that he felt “hatred against Japan” and was ashamed to be born in a country that would do such horrendous acts.