5週2日目 あの人のことだから
Evaluation・cause・basis
接続：Nの＋ことだから
because it is a person or thing with that characteristic
注意 / Note：The first person must be a PERSON whose personality both sides know, because the whole sentence is a guess based on that person's personality. The latter is almost always 〜だろう・〜はずだ・〜に違いない. Don't confuse it with 〜ものだから (give a reason) — the letters are close but different.
比較 / Compare：Same song: 〜ものだから／〜ことだし. These models are often mistakenly chosen for each other — carefully read the 接続 and nuances above and then decide.
よく出る形 / Common form：名詞の＋ことだから、〜だろう／はずだ。Preceded by a person's name or a pronoun indicating a person.
真面目な彼のことだから、約束を守るだろう。
Because they are serious people, they probably keep their word.
田中さんのことだから、もう来ているはずだ。
Since it's Mr. Tanaka, he must have arrived already.
几帳面な彼女のことだから、もう準備は終わっているだろう。
She's meticulous, so she must have already prepared it.