At the end of the day, users will just see that a website works in Chrome and not in Firefox. Firefox will decide that there is no point in apposing it if there is a real cost in potential market-share.
Remind me, how has that strategy worked out for their market share? Perhaps the market for I-Can't-Believe-It's-Not-Chrome isn't actually that big since those users don't have a problem with just using Chrome.