Toji was doing a good job of distracting the woman on his own, Meta need not do anything. But, when the woman started to get angry and form an aura, he knew she was up to something. Not the best observation in the world. Toji probably knew what to do anyway, but Meta decided to say it anyway Toji, get some distance from her! Then, when it exploded, he held his ground and then turned to lead, with the lead properties reducing the damage and his new weight stopping him from being sent flying too far, he just got pushed back a few metres. He would then look over to the scientists and Yang, and decided to stay out of the way for now.