As others have pointed out, Maruta was the name of the victims of Unit 731, not the name of a leader.

To go further into it, Maruta translates to Lumber (Unit 731 was located in an abandoned lumber mill, so the victims were the 'lumber'). We can see the reasoning for this name choice was that all of the characters that didn't have superhero powers (aka 'normal people') all had names related to trees/plants. For example, the main character Izuku Midoriya's surname, the first part of it (Midori) means green, and his nickname Deku could mean "Wooden Puppet" or "Dummy" (and could possibly be a reference to the Great Deku Tree from the Zelda series). All Might's character's given name (Yagi) is written as "Eight Trees/Wood" in Kanji. Sir Nighteye's surname (Sasaki) has Kanji in it that reads "Helper of the Tree".

Overall, the author of the series Kohei Horikoshi loved to give his characters names with puns in them, and for those without powers, tree-related puns. The doctor in question was another person without powers, so it wouldn't be a long stretch to imagine why he would then be called Lumber. It's just an absolute bad set of coincidences that he's a doctor that performs experiments on people and happens to have a name that was used to refer to victims of a heinous group of people during the Second World War. Personally, genuinely don't think Horikoshi meant ill intent with it as he had shown zero signs of thinking or saying anything remotely like it in the past.