Batman doesn't sound so crazy anymore, does it! More power to you my friend! I hope you do name him Batman! I support it!
50 craziest celebrity baby names (in alphabetical order)
Aanisah: Macy Gray (also mother to Tahmel)
Apple: Chris Martin and Gwyneth Paltrow
Astrella Celeste: Donovan and Linda Lawrence (also parents to Oriole Nebula)
Atherton Grace: Don Johnson and Kelley Phleger
Audio Science: Shannyn Sossamon
Aurelius Cy: Elle Macpherson and Arpad Busson
Blue Angel: U2's The Edge and Aislinn O'Sullivan
Bluebell Madonna: Geri Halliwell
Brooklyn: David and Victoria Beckham (also parents to Romeo and Cruz)
Calico: Alice and Sheryl Cooper (also parents to Sonora Rose)
Camera: Arthur Ashe and Jeanne Moutoussamy
Destry: Steven Spielberg and Kate Capshaw
Diezel Ky: Toni Braxton and Keri Lewis (also parents to Denim Cole)
Fifi Trixibell: Bob Geldof and Paula Yates (also parents to Peaches and Pixie)
Fuchsia: Sting and Frances Tomelty
Gaia: Emma Thompson and Greg Wise
Gulliver: Gary Oldman and Donya Fiorentino
Heaven: Lil' Mo (also mother to God'Iss Love Stone)
Heavenly Hiraani Tiger Lily: Paula Yates and Michael Hutchence
Hopper: Sean Penn and Robin Wright
Ireland: Alec Baldwin and Kim Basinger
Jaz: Steffi Graf and Andre Agassi
Jazz Domino: Joe Strummer
Jermajesty: Jermaine Jackson and Alejandra Genevieve Oaziaza (previously married to Jermaine's brother Randy)
Kal-El Coppola: Nicholas Cage (Kal-El is Superman’s original birth name)
Kyd: David Duchovny and Tea Leoni
Lark Song: Mia Farrow and André Previn
Lennon: Liam Gallagher and Patsy Kensit
Liberty: Ryan Giggs
London Emilio: Slash
Luna Coco Patricia: Frank Lampard and Elen Rive
Marquise: 50 Cent
Memphis Eve: Bono
Moon Unit: Frank Zappa, also father to Dweezil and Diva Muffin
Moxie CrimeFighter: Penn Jillette (also father to Zolten)
Ocean: Forest Whitaker (also father to Sonnet and True)
Pilot Inspektor: Jason Lee and Beth Riesgraf
Poppy Honey: Jamie and Jules Oliver (also parents to Daisy Boo)
Rocket: Robert Rodriguez (also father to Racer, Rebel and Rogue)
Rufus Tiger: Roger Taylor also father to Tiger Lily and Lola Daisy
Saffron Sahara: Simon and Yasmin Le Bon (also parents to Amber Rose and Tallulah Pine)
Sage Moonblood: Sylvester Stallone and Sasha Czack (also parents to Seargeoh)
Satchel: Spike Lee and Tonya Lewis Lee
Seven Sirius: Andre Benjamin and Erykah Badu
Shiloh Nouvel: Brad Pitt and Angelina Jolie
Sosie: Kevin Bacon and Kyra Sedgwick
Suri: Tom Cruise and Katie Holmes
Tallulah: Bruce Willis and Demi Moore (also parents to Scout and Rumer)
Willow Camille Reign: Will Smith and Jada Pinkett-Smith
Zola Ivy: Eddie Murphy and Nicole Mitchell
He can name his baby whatever he wants. Its okay. At least he isn't naming his child Nosmoking [Noz-mo-king} or shithead [shi-theed] both of which my aunt who is an elementary school teacher has come across.
MJ names his kid blanket...
I told my mother about this, and she thought it was disgusting. I personally think it's not so bad. It's kind of cool. 
As these people ^^ stated, it's really not so bad in comparison with a host of other names. I'd rather have a kid named Batman than Blanket, Camera or Jermajesty. lol
The parents could easily name their kid [boringly typical first name] Batman [last name] instead of Batman as the first name. Or, even better, Bruce Wayne [last name] and call him Batman for a nickname.
The kid can always change it when they get older, but, as someone else has said, the father in question here will no doubt expose this child to all that is the world of Bruce Wayne and Batman. The kid is going to think his name is cool. 
Besides, the names John, Michael, Steven, Mark, Andrew, Robert, David, Harold etc have all been done to death anyway. 
(Note: Even though I do think it's nuts when people name their kids after Nazi's, terrorists and other evil and sick individuals, a parent has the right to name their kid what they want. We don't all have to like it, and, frankly, neither does the kid (I hated my name Mindy for many many many years). In the end, it's the person, not the name of the person, that matters.)