Yes, he is. You just haven't really thought this through.
Think about it for a second: he's in town to do a specific job. That job involves constant negotiations with Evelyn. In other words, if Evelyn is busy (ie. not at home), that means she's working, and if she's working, Thaddeus is working.
The only way Thaddeus could "never" be available is if you cannot help yourself whenever Evelyn is home and instead spend time with her. That she's home in the afternoon means that Thaddeus is available as well. You need to choose between the two.
He is literally never available in the mornings and evenings, though. You need to seek him out in the afternoon.