The 'own use' termination cannot be contested.
Of course it can!
Envisage this scenario -
Moon Light gives her tenant 56 days' notice of termination citing the "own use" ground. 56 days come and go and the tenant fails to vacate the property, saying she has nowhere else to go. So, Moon Light has to seek a Determination Order from the RTB. The average processing time for such cases is approximately 5 months, this is from application received to Determination Order issued where no appeal is received.
So Moon Light now has her determination order but her tenant still fails to vacate the property. So now she has to go to Court.
Where the terms of a Determination Order have not been complied with within the specified timeframe, Moon Light can opt to enforce their own Determination Order through the Circuit Court (which is costly). Alternatively, she can apply to the RTB to initiate enforcement proceedings against her tenant. Needless to say this all takes time.
After all that, the tenant could still subsequently dispute the grounds upon which the tenancy was terminated! In other words, she could complain to the RTB after she is evicted that Moon Light did not in fact require the property for her own use.
The whole process is so long-winded that opting for the root with the shortest possible notice period at the outset seems like the better option to me.