People I think defend it in the same way as prosecuting Al Capone for tax evasion: we'll take what we can get. In the context of things like the "Halloween memos", funding the SCO controversy, and various other bits of anti-interoperability work people were just grateful for an impairment of the platform monopolist.
Nowadays Apple has a policy of banning all other web browsers and even program interpreters from its platform. This isn't really acceptable either, but there doesn't seem to be any prospect of doing anything about it.
Apple doesn't ban web browsers, they couldn't give a rat's arse about that. They ban PROT_EXEC.
Apple's position is essentially that iOS already has a perfectly good JavaScript engine (JavaScriptCore) and the security risks of allowing apps to use mprotect/mmap far outweigh the benefits of allowing other JS engines.
Nowadays Apple has a policy of banning all other web browsers and even program interpreters from its platform. This isn't really acceptable either, but there doesn't seem to be any prospect of doing anything about it.