The issue is the second point. It was pretty obvious that public keys can be compressed, but whether that created an intrinsic failure while implementing this was at stake.  Also, without the compression there may be other fun mathematics possible.

For some things that Satoshi did not comment on, I believe it to be more of a caution and implementing carefully, knowing that there are limitations to an individual and even organisations debugging code. The main principles were his insight, while implementations in all code requires a larger community and prolonged testing (which bitcoin has been successful at).