depends if they spin or not...if not, they can use two hands but even if they didn't, if a person wants to, they can generate a ton of power with their right or left hand by doing an open-handed (sometimes called a "roll") shot...
quick note, the rule says it could be considered a distraction, see below...I have also include a link to the rules which you may find helpful in other ways because he may be "Jarring" which can happen even if you are a shooter
23.4 It is legal to have just one hand on the rods when playing defense (example: right hand on defensive five-man). It is also legal to use two hands to move one rod (example: defensive five-man). Excessive switching of the hand between the handles may be judged a distraction.HOW TO STOP THIS
If you can't just stop this with the rules, how can you deal with it? Here are a couple ideas:
1. Everyone who isn't his guy and who talk together should agree to tell him repeatedly that you all don't approve
2. Everyone should make fun of it as often as possible to create peer presure...only untalented loosers use both hands, this is bush ball, pu$$y shot, etc...you know, dog him
3. this is the best strategy...STOP him...make him look stupid...you can get infront of the ball and put together defense to stop that kind of crap...well at least 90%+ of it - so much of it that the person will stop doing it in pretty short order
* He has a big wind up and you should be able to tell which side of the ball he is going to crack it on...get the 3 bar man infront of this with the toe of the man point toward the shooter, to the side of the ball he is going to be angling it too (opposite of the side he is hitting on)
* on the side of the table that the ball will be hit to, keep your 5 bar about one inch off that wall toe pointing toward the shooter (just like on the 3 bar)...don't jump or you will loose this valuable position and advantage
* Have your goalie move his guys so that the goalie middle man is pulled all the way to the wall (literally) on the side the guy is hitting to and put your 2 man rod in one of two positions...either about 1/2 inch outside the small box line or about 1/2 inch inside that line...both will be effective
if you do this, you have to be disciplined enough to hold your ground when the big crack comes...if you can be on the side he is hitting to, in these positions, and not move, you will cut off 80% of his scoring...a lot of them will come right back at him, or bounce to one of your men, or bounce off the table
there are some shots that may need you to adjust some but be careful that this adjustment is a jerk reaction which pulls you out of the way
there are other defenses to cut this kind of thing off but this will be effective...main thing is, you and the other players need to learn this or create your own...think about the the men you have to work with and what kind of zone you can create to cut out as much random slop as possible
as annoying as this can be, it is your responsibility as a defender to be able to stop slop...if slop goes in, I contend it is never the offensive player's fault...they shouldn't be proud of it like they did something special but even if they are, you need to not let that get too you because it impacts your play...take responsibility for what you can control and get better at defense
if your game gets better, some day you will thank this guy for making you learn to stop slop
http://www.table-soccer.org/rules/documents/ITSFRulesEnglish.pdf