Apple doesn't legally owe gold rush developers a livelihood, but the ethics are not so clear cut, especially when they pull a Facebook-like policy switch after people have already invested.
...but honestly, how many devs would've turned around and walked away if they had?
2) Apple changes section 3.3.1 in the developer agreement for OS 4.0.
3) You have to spend the time and possibly money to learn a new language if you want your application to work on OS 4.0, or forgo your previous investment of time and money. Most iPhone OS devices will be upgraded to 4.0 relatively quickly.
Legal? Probably. Justified from Apple's point of view? Likely. Reasonable, fair or ethical? That's pretty subjective.
See, this right here^^^ This is the key: why did you decline the offer from BigCorp? Only two reasons I can think of...
1. You were naive and thought you could make a quick buck with less work by developing for the iPhone platform without doing it the way Apple suggested you should.
2. You had the drive to strike out and make it on your own, BigCorp be damned!
If it's #1, you only have yourself to blame. If it's #2, you're not about to let something like 3.3.1 stand in your way...
Now he has to either train them too in Obj-C or recruit a new bunch of Obj-C developers.
To top it all off, he must stop improving his product and start rewriting it in Obj-C, while his competitor who started off with Obj-C doesn't have to. There was nothing in the previous version of the OS agreement to suggest that cross-compilation would somehow be banned in future versions. All because Steve Jobs, loves Obj-C. Now how isn't that screwing people's livelihood?
Take out the job offer from bigcorp from my example. You're still going to have to invest in hardware and probably ramp-up.