the timeframes come from the time limit within which someone like you (ie a dismissed employee) can take case - 6months noremlly (12 in exceptional circumstances).
so it really realtes to the risk of someone taking a case against them rather than a bar on taking on new staff. If you think about it, it would be preposterous to have a time limit imposed on employers stopping them taking on new staff.
At your claim, you can point to the expansion as a reasons why your dismissal was not a proper redudancy scenario. However, they will likely counter that the situtaion changed for the better, which in fact would justify their decision to take the steps they did, and it was only when a much improved market/economic situation arose that they can now re-hire.
ie, its not fatal to their defence but a little helpful to yours - not a silver bullet, just a whiff of cordite!
currently 46 weeks (yet forty six) dealy for claims to reach hearing stage in Dublin