This type of も does not mean "also". In this case, it adds the nuance of "of course", "it's only natural" or "it's no wonder". It usually followsis used with something that describes a reason or a cause.
- 昨日から何も食べてないの? そりゃ、お腹も空くよ。
- 昨日から何も食べてないの? そりゃ、お腹が空きもするよ。
- 全く連絡がないんだから、心配もしますよ。
- たった1000円なら、流石に買えもしますよ。(=買えますよ)
- そんなに悪く言われたんじゃ、彼も怒るわけだよ/彼が怒りもするわけだよ。
In this manga, the reason part is added after the result part.
It's hard toI could not pinpoint the specific definition in a monolingual dictionarydictionaries, but basically this should be related to "exclamatory-も" or "も to make the sentence sound reserved". This も is used to vaguely describe "how things turn out naturally".
You can find the same も in the のももっともだ construction, too.