First of all, I have to admit that I'd never heard of the word estoppel until now. I checked the OED (Oxford English Dictionary), and it says:
1 An obstruction (to a watercourse) whether natural or artificial.
2. Law. An impediment or bar to a right of action arising from a man's own act, or where he is forbidden by law to speak against his own deed.
b. gen. Stoppage, prohibition. Obs.
Based on that, I'm not entirely sure you can use it the way you suggested. I found only 2 cases in the British National Corpus, and both were related to law.