If the pill genuinely expands 100-fold in your stomach then I can see it being worse than throwing up. Either it might suck all the fluid out of your stomach, in which case you won't be able to throw up, or it might fill your stomach so rapidly that you can't bring them all up in time.
Of course I'm sure that the consequences of overdose are something the researchers have thought about carefully and probably tested on animals by now.
You should be able to throw up even if it sucks the fluid out of your stomach. The muscles would still work, and the stuff should be slimy enough that it's not going to scratch up your esophagus.