I don't know if being upfront about the financial motives when first announcing Patinkin would have been the best move. The purpose of casting Patinkin was presumably to entice some people to buy tickets who otherwise would not have; and that would have kept the cast and crew (excepting Oak, sadly) employed for longer. Saying "our show is so amazing that this Hollywood and Broadway star begged to be in it!", as they did, might have sold a few tickets; but coming right out with "our show is in its death throes and we were so desperate we had to shaft our poor lead actor", not so much. A show's producers and/or PR team aren't going to gain any new interest by acting as though their own show is a loser rather than a winner. The fact that they're talking openly about the show's financial troubles now, IMO pretty much shows that it's definitely about how, not if, the show closes at this stage.
Although I feel for Onaodowan, I wish that Patinkin (and even Malloy) had held firm and just gone ahead with Patinkin's casting. I get that they feel the need to protect their 'personal brands', but choosing to do so right now will actually hurt the show's prospects and, by extension, the rest of the cast and crew. (Quite likely the show is fated to close soon regardless, but nevertheless.) And giving in to outrage culture like this will just validate it and make it that much more likely that other friends and colleagues of theirs will get burned by it in the future.