Im totally suspicious of old people too. They're the enemy man
As far as topping flowering plants, it will not kill it. However you cannot expect the plant to regenerate that part vegetatively to the extent required to make good buds. So you would be relived of a high stalk but would receive none of the other benefits of topping like the twin colas ect.
Iv transplanted the day I started flowering to no ill effects. Transplanting wont kill your plant either but the issue is that during flowering the plant is not prioritizing resourses for root growth, it is focused on producing buds. If you transplant now that its budding the transplanted plant will divert resources towards root growth that will be detrimental to the final product.
These are situational judgments. Not knowing as much about your situation I cant offer anything but general advise but in my experience if you want to top for some benefit you would need to do it at least a week prior to flower, at the latest maybe a week or two after. The only reason to do this is to allow you light to reach the majority of tops when you have 1 guy who got huge.
And as far as the pot, instead of repotting or xplanting just use stronger flowering nutrient regimin to offset the roots being bound up in a smaller pot. This requires experience with nutes so you dont burn anything.
But whats your situation? Are you growing indoors under lights? You mentioned xplanting outdoors, why?
