But as a diet, this would be glucose spikes multiple times per day, for perhaps a lifetime. That may not qualify as "toxic" I guess, in that it doesn't kill you on the first day. But it is not benign.
Rice is commonly eaten mostly because it's easy to grow in wet climates, and it's a cheap source of calories. I eat rice myself, but let's not be fooled into thinking that rice and other grains are particularly healthy. Small amounts are fine, but if you get the majority of your calories from grains or consume large quantities in a single meal that cause blood glucose spikes that certainly isn't ideal from a health and fitness perspective. Everything in moderation.