Probably not. There doesn't appear to be any evidence of the exploding stomach phenomenon. And most evidence to be found points in the opposite direction.
Seeds are a natural food source.
This is a study of the diet of one type of Ant in Oklahoma. And seeds are listed as an important dietary item.
At grassland and pasture sites, seeds (17.2 and 15.7%, respectively) were
important foraged items.
Is grain substantially different than flour for ants?
The size of the particles swallowed must be smaller than typical flour.
Almost all wheat flour particles are larger than the esophagus of the ant (~45µm).
Can ants eat solid food? Regurgitate?
THE INFRABUCCAL POCKET OF A FORMICINE ANT: A SOCIAL FILTRATION DEVICE
This paper goes into how the ants feed, if I may summarize. The ants feed on liquid food (workers, at least, can't feed on solid food). Relatively large solid pieces are caught in a special cavity, when this cavity is full, the particles are ejected as a single pellet. The filtered food is regurgitated and shared with other workers, who in turn also filter the food.
Actual measurements made with species of Formica, fed on food labelled with radioactive
tracer, have shown that the crop contents from single foragers may become shared by an entire colony in a matter of hours (Wilson and Eisner, I957).
The closest I could find about feeding flour in particular to ants just involved using it as bait for collecting specimens. No mention of exploding stomachs was made.
Meat, flour and sugar baits were used on the soil surface and buried to examine species composition of the ant fauna in three separate tropical forests in Brazil, and to control for the effect of the regional faunal pool.
Caveats These papers look mostly at the worker caste of the red imported fire ant. Results could be different for different types of ants. This assumes nothing special about the flour besides being ground seed.
Conclusion, Making the assumption that the reason people think their stomachs will explode is because the rice/flour will expand once in contact with water, rupturing the stomach (violently?), I think I have presented enough evidence to show that this won't be the case. The food must already be in contact with water before consumption. Seeds are naturally eaten by ants. Ants constantly regurgitate their food to share with each other.