I guess the pseudo-magic rule #1 says that any continuous magic remains on during time stop. Neat concept, but it could lead to flooding if a magic water faucet is left alone for too long.
Rule #2 says that gravity still applies to those under the effect of time stop and everything they try to touch. If not, brobot would have jumped into the air and held onto the suspended cockatrice forever. (But why was the cockatrice using a petrifying beam at all when not under attack, unless the page forgot to show that MC revealed himself to the boss before he stopped time to build the stairs? Or the petrification is a passive ability. Scary.)
Final point: MC did brobot dirty by not letting him come along to the unpetrified bathhouse. Dirty, I say.