Before rushing into criticism, lets get a few facts right. A derailment of an engineering train at Winsford, see
http://www.railforums.co.uk/showthread.php?t=60841
caused a blockage of the WCML affecting Virgin Trains between Euston - Liverpool, Euston - Glasgow and Birningham Glasgow/Edinburgh, also LM Birmingham Liverpool. The first northbound train to pass Winsford was 1S67 1225 Euston Glasgow at 1525, and the first southbound was 1A46 1448 Liverpool Euston at 1545.
Therefore there were no direct trains between Crewe and Preston before this apart from a special Voyager which ran a 1Z01 1132 Crewe to Preston and
1Z02 1300 return via Chester. The first train from Preston through Winsford was 1M13 1242 Glasgow to Euston which started from Preston at 15.12.
Other than this trains from the north terminated at Preston and those from the South at Crewe, with the sets used to form restarted trains north and south respectively.
I surmise that most people from Preston were sent forward via Manchester, but between Preston and Manchester capacity is limited, so there could well have been a backlog of unhappy people decanted from Glasgow and other trains at Preston unwilling or unable to get on TPE trains to Manchester.
Therefore when 1M14 1336 and 1M15 1436 Glasgow to Euston left Glasgow they would have done so in the expectation that the line would reopen, but at that point it was still blocked. My guess is that VT control would have known about the situation at Preston, and Glasgow may have been told to limit the numbers joining so as to leave room for said backlog of people and to spread the load to allow services to return to normal more smoothly.
The reason for the Crewe stop would have been that the preceding train
1M57 1355 Glasgow to Birmingham started from Preston, so 1M15 would have provided a connection from Glasgow to Birmingham.
So yes it may have eventually proved to be a wrong decision, but was taken without the benefit of hindsight.