It's just a rubbish reply, isn't it? It makes him sound like he is about 12 years old.....
I have at times used OLD with the intention of finding casual partners/ONS, and even I would have been pyt off by this!
Just trust your instincts. If they say something off putting to you, cut it off.
As for the age difference thing, I am in my 40s and would consider dating 10 years younger (were I single) but would be concerned, if I was looking for even semi long term, they might have different expectations in terms of wanting more kids. Life stage is possibly more important to determine than the pure numbers of age. Depending what you are looking for, of course.
It's slim pickings out there but I did meet the love of my life on OLD, and despite both being far from perfect, and various stumbling blocks we have faced, we are still going strong four and a half years in.
The best advice I can give is to know what you are looking for. Some people crave stability, some might be desperate for companionship and shared interests. I wanted passion and someone who rocked my world....
And don't settle for anything less. But enjoy the process in the meantime. Go on dates, have a laugh, see the funny side, and keep your powder dry. Don't get invested till a long way down the line if you. can possibly avoid it, and don't go excluosve until you know they are - don't necessarily mean in terms of shagging, ( though that too if you like,)but in OLD it is permissible and normal to be chatting to/dating a number of people until you are ready to fully commit to one.
And good luck!