do i believe that china just stopped transmission?

not really.

they more likely stopped publishing data.

when iran was suspected of fudging the numbers, we were able to pick it out through statistical analysis. i would be highly skeptical of claims coming from the politburo until they can be verified independently.

but, i would suspect that so many people in china may have come in contact with this at this point that they may have substantial immunity building up in the population. 

if the lockdown helped at all, it would have been in keeping vulnerable groups inside - but they could have done that with less severe restrictions on the general population. if you piss all over the wall in a drunken fit and you manage to moisten the flower bed, that's not any particular measure of success in the task of watering the flowers; citing overly broad measures to contain a small group doesn't justify them, that's just poor logic.