Is that low transverse incision on his lower stomach a c-section scar?

Looks like it.

From what I can see, yes. Which would be an indication he gave birth, but I guess ML wouldn't notice in the moment.

Since he said he’s a beta, it doesn’t raise any suspicion

Ah. Okay.

And he works in a security company so figures that he would get hurt and have scars.

Yep