As for whether Tobirama Senju would immediately try to kill Madara after he summoned Hashirama through Reanimation Jutsu...
Madara wasn't worried in the slightest.
It wasn't just because he himself was currently in a Reanimation Jutsu body. No one in this era knew his true goal except Black Zetsu and Obito (Naruto: Sorry, there's one more person who knows.)
Tobirama might suspect him, but he definitely wouldn't act rashly.
Madara was confident of that much.
Of course, the most important point was that Namikaze Naruto intended to destroy Konoha!
As long as that fact remained unchanged,
Hashirama and Tobirama would inevitably clash with Namikaze Naruto first.
And that would be
the perfect opportunity for Madara to make his move.
Madara knew
exactly how strong Hashirama and Tobirama were.
There was no need to mention Hashirama. Tobirama's strength was only a fraction below his and Hashirama's. Even someone as proud as Madara acknowledged Tobirama's abilities. The intense hostility he had once felt toward him was proof enough: Madara would never feel such strong animosity toward someone he didn't respect. And the kid was clever, too. That was Madara's opinion of Tobirama.
In short,
there was no problem with summoning Hashirama and Tobirama here through Reanimation Jutsu.
Although relying on—or, rather, making use of—Hashirama's power made the ever-proud Madara feel somewhat uncomfortable, it was all for the sake of the Eye of the Moon Plan.
It was all to bring true peace to the Shinobi World as soon as possible!
For that,
Madara was even willing to do things that went against his nature.
Ninja
were beings who would stop at nothing to achieve their goals.
Madara might have been a little different, but the essence of who he was as a ninja hadn't changed much. That was one of the reasons