During scaling there may have been bleeding if your gums were inflamed. In such cases there may be a little bleeding through the day. So perhaps as a precaution they may have asked you not to spit so that you don't get afraid in case you see blood. Quite frankly it doesn't make a difference as long as you know seeing a bit of blood in your saliva post scaling is ok.

Hello there. What to not split? Didnt quite get you. Regards