Yes, but that answer is wrong, because of a quirk about umbrellas themselves - Orthodox Jews don't use umbrellas on the Sabbath because opening an umbrella bears some similarity to constructing one, and constructing things is forbidden for them on the Sabbath. (There are many, many footnotes that would be needed to give a full explanation; in short, Orthodox Jews don't use them, regardless of whether they actually believe they "should" be forbidden from first principles.)

I was raised as an Orthodox Jew, but have gone off the derech (I no longer believes in Judaism and do not practice it anymore) an Orthodox is not supposed to use (and carry) money on the Shabbat, or even supposed to carry umbrellas, even inside an eruv[1] for those who believes in its validity (The Jewish law is not a monolithic concept, it's basically discussed to interpretations which the majority agrees).

It's common to see religious people going to the synagogue in raincoats in the Shabbat in neighbourhoods with a large Jewish community.

Anyway, this is not the point of the article.

[1]: http://en.wikipedia.org/wiki/Eruv

EDIT: The guy can sell umbrellas in the religious services in other days which are not holidays or shabbats, there are three religious services each day, the maariv, the shacharit and the mincha.