It depends on the workload. For sustained workloads, yes, it would bring you closer to throttling.Those two extra cores would also just bump an Air closer to thermal throttling if they made much performance difference.
For bursty workloads, possibly not, as 1) it could get more work done in a shorter amount of time, and 2) since the higher core count chip may be slightly more efficient than the lower core count chip, it may generate less heat doing the exact same work.
And under the sustained workload that increased efficiency may still result in better performance.