He can certainly be both a Marxist and a corporatist, seeking to limit capitalism while simultaneously making deals with large corporations. It only takes being smart enough to realize that Marxism inevitably leads to poverty. Therefore a smart socialist seeks not to wipe out capitalism, but to control it and control its product. It's called picking winners and losers; you scratch my back and I'll harm or destroy your competition while giving you tax breaks. Congress does this all the time with the tax code and sometimes with other laws. To wit: I'll enact a crippling health care bill, then I'll let my friends opt out, thus gaining a competitive advantage over my enemies (i.e. capitalists who don't give me money and say nice things about my initiatives.)
I'll agree with Jhhnn's response that this is pretty strained spin-jobbery, and I'll add a more specific comment. What you are describing is not Marxism by definition. The Marxist doesn't "preserve" capitalism. What you're describing is just the mixed system that we've had since the early 20th century, that exists to varying degrees throughout the entire developed world, and you're putting a negative cast on it. Even if your negative spin were true, it still isn't Marxism by definition.
No, I'm afraid the point stands - he can't be a Marxist and a crony capitalist at the same time. He could incorporate some elements of each into his governance, but he couldn't accurately be described as either. It's like saying I'm a Marxist because I believe in single payer healthcare, but a corporate shill because I don't fault Obama for not prosecuting Wall Street more vigorously. Neither label is correct.
In Amercian ideological terms, Obama is essentially what we call a moderate. Not really very different from Clinton, who incidentally was also called both of these things repeatedly.