Boiler ???

Ok heres what happened... My sister called me with a no heat situation after calling her landlord and he was bowling so he couldnt come and look at it, he told her to just "bundle up tonight". I'm thinking this guys an as*hole my neice and nephew are going to be cold and his bowling is more important.... So I go take a look its a dunkirk 2 burner boiler with 2 zones, 1 small loop upstairs and then the entire downstairs on the other. So I check pilot first, pilot is lit. I then look at the thermostats to see if they are calling for heat. the downstairs one was not calling for heat, but the upstairs was. So I go back into the "boiler room" so to speak, actually just a big closet.
I notice then that there was a manual shut off valve about 6 inches past the zone valve and it was CLOSED. So to me this was the reason for the no heat condition when the first floor called for heat because whil the first floor was at temp the upstairs was constantly calling for heat, but not getting any which caused the boiler to heat up and shut down cause it couldnt move the water. So if it did this cycle constantly would it cause the boilers controls to not allow it to fire. So I then did as the manual said to turn off both thermostats for 1 minute so that the controls could reset. I turned them off and I opened the closed shut off valve that was blocking the zone. Few minutes later I turned on the upstairs thermostat and the boiler kicked on circulater started and it was now able to move the water through the zone instead of heat up and shut down. So I tried both thermostats independantly and they both properly controlled the boiler and all was well. So my sister called the landlord to tell him thet her brother fixed the problem well he wanted to talk to me so I told him what i thought was the issue and why the boiler wouldnt produce heat. He said the upper zone was disconnected 1 year ago and it never happened before. I told him whoever disconnected did it wrong and the extremely cold temp here in NE US is what finally got the upstairs cold enough to call for heat and when it did thats when the unit stopped. He insisted it was something else and he was gonna send "his guy" anyway. I'm thinking geez i hope this isnt the guy who just closed the valve to disconnect the zone. So I left and told my sister to call me when "his guy" left and tell me what he said. So the question is, Was I right???