This problem can be solved and may not be an optimal solution is write a function in terms of object arrays, NOT USING CELL ARRAYS THAT REFER TO DOCUMENTION.
function dstORBPoints = getSubInds(srcORBPoints,validIdxs)
%#codegen
Location = srcORBPoints.Location(validIdxs,:);
Metric = srcORBPoints.Metric(validIdxs);
Scale = srcORBPoints.Scale(validIdxs);
Orientation = srcORBPoints.Orientation(validIdxs);
dstORBPoints = ORBPoints(Location,"Metric",Metric,"Orientation",Orientation,"Scale",Scale);
end