Yes it is on any age.
Get one around 500cc or 750cc instead. I am 6ft tall and they are fine. Also, NO full fairings. Since you pretty much are going to dump it somehow. Then will look like crap. When you know how to ride it, you should be fine with a nicer bike. I have a KLR250 that I bought 20 Years ago, still works and I drive it once in a while. I bought it to get my Motorcycle Endorsement. Is much easier to learn and get the Lic on a dual purpose bike. The handle is better, is lighter and a piece of cake to get around the obstacles. I saw a guy with a Ninja 250 and failed since the bike ridding possition is hard to make tight 90 deg corners (stop-look-lean-roll-ease the clutch out).
Is that what are you looking for, that is the way to go. You can get one dirt cheap and sell it dirt cheap too. My boys learned how to ride on the same bike too.
If you buy a 250 or so, you will out grow the bike rather quick. So my best friend I suggeted him to get a 550cc Yamaha, Street bike, was a Maxim 550cc. Good seating and ridding possition. He learn on it and got his lic too on it. Also used the bike to commute too. Decent power but not blazing fast, but enough to raise your eyebrows from time to time. That was back in the late 80s.
Is not all about power and with out control is worthless. You need a bike that you can handle. On Super Bike racing they use 750cc and that is big. Is a balance between handling and power. If the bike is too heavy is hard to park and move around parking lots. Too light and the wind will play with you like a kite.
What I do is, sit on the bike and tip on the sides and see how far can I hold on to it. If is hard to hold on to it is not a bike that I will not like. Sometimes you find uneven roads that you have to stop and one leg steps on a dip "hole" and the bike tips too much on its side. Making it hard to hang on to it and hits the road. Also, you have to be able to pick up from the ground, in case you have to.
I hope my experiences helps you !