in a perfect world arbitrage betting indeed has no risk since you are betting all the possible outcomes and benefiting from the different odds in different sites
BUT almost all sites are against arbitrage bettors ( except few asian ones ) which means sometimes the books may void your winning bets so you end up losing
I partially agree with you here. Sportsbooks only void bets in certain cases(Match suspended, Player retired etc) and not because you placed an arb. They generally limit or ban arbers, but allow them to withdraw their winnings(Reputable sites like Bookmaker etc).
Op is clearly advertising something which everyone know and there are softwares out there(Rebelbetting, Betburger etc) to help with this which is why what he is offering is pointless.