It seems odd. However, depending on the circumstances it might not be entirely unreasonable. As for whether it is legal, the EC can ask any question it cares to ask as a survey but ultimately major decisions generally require a general meeting to make a resolution.
I recall one occasion when our EC conducted a poll. The debate was about whether to have a particular facility and, if so, where to put it. There were many suggestions for where it should go and support or opposition depended for many people on where it would go. So, we asked people to fill in a survey. We listed every suggested location, including the ones that were ridiculous, and asked people to indicate for each suggested location, was this the best location? was this a satisfactory location they could support? would they oppose the proposal if sited in this location? Out of that there was one location with clearly more support and less opposition than any other and a motion was then put to a general meeting to install the facility in that location.
So, I don’t know what your EC is up to but conducting a poll might not necessarily be unreasonable.