The problem is - if a node is unmanaged, create transport fails and I am unable to run the script.
If it is in maintenance - it is fine.

Therefore the question is - if unmanaging a node prevents me from creating a transport, is there an alternate option to check snmp response whilst node is unmanaged?

transport = CreateSNMPTransport ($node);// Create SNMP transport for node
println $node->name;
if (transport == null)
{
  println "Failed to create SNMP transport, NetXMS is very unhappy, DONT poll unmanaged nodes exit";
      return $1;
}
value = SNMPGetValue(transport, ".1.3.6.1.2.1.1.1.0");
if (value == null)
{
    println "Failed to issue SNMP GET request as no SNMP response - might be community, might be connectivity - try pinging the node first!!";
       return 2;
       }
       else
       {
         println "SNMP request responded to our request for sysdescrt - and here it is ::" . value;
         return 0;
}