I would have thought tá seisean would be a better translation here since the emphasis in the English sentence is on he.
It would be, but the sentences here rarely (if ever) use the emphatic pronoun forms.
EDIT: It’s accepted as of 2015-08-17.
Here we have contrast, no emphatic form, but two exercises ago omitting the emphatic form was marked wrong!
What does fáil mean?
ar fáil is a prepositional phrase that means "available". fáil on its own has several meanings, see
As the fáil is the verbal noun of the verb faigh, it might be helpful to think of ar fáil as get-able.
This is just a minor mistake I could still tell what the question was asking, but it asked me to translate, "I am notavailable, but he is." Just a suggestion to fix that minor detail :)
"Ach tá sé é" was wrong. I dont know why I just want to throw "é"s and "í"s at the ends of sentences when we're talking about pronoun people!