On the second thought, a reasonable design can use datetime.min/max as placeholders for unknown times far in the past/future compensating for the lack datetime ±inf.  In this use case, it may be annoying to see errors from timestamp() instead of some ridiculously large values.

I am -0 on making this change.  If anyone is motivated to produce a patch - I'll review it, but I am not going to write it myself.

I am marking this "tests needed" because we need a test complete with setting an appropriate timezone that demonstrates this issue.