I think the whole "stabbing" incident was entirely staged.

Check out this out from Cine-Shock-O'Rama:

Cruel irony, or mere community theater on the high seas? Bespectacled mid-season replacement Joey Greco, whom devotees swear stabbed ousted "Cheaters" host Tommy Grand in the back, was himself ventilated with a fishing knife over the weekend. The grisly attack capped the "real reality" TV phenom's most embattled season as the leering press, including GQ magazine, have increasingly pondered "Is Cheaters Cheating?" by sweetening or completely cooking delicious "true" stories of covert canoodling. Now there's even more blood in the water.
In a syndicated finale truly worthy of May sweeps, a six-month mother to be is motored into the middle of a LAKE to confront her philandering babydaddy who's found fishing, shirtless, as his new honey sunbathes topless. Soon blurry-faced "Mitchell" tires of Mr. Greco's judgmental needling and lunges for the diminutive host's waist, touching off a melee as security goons spring into action and simultaneously send a member of the Cheaters crew tumbling into the lake. However, just as the boat-borne tussle settles, someone yelps "Blood! Joey's bleeding!" and viewers are unceremoniously confronted by the ghastly result of a "3-inch" puncture wound to Greco's lower-left abdomen. The show then came to a chilling close with Joey being rushed ashore to the care of paramedics -- all as cameras continued to roll.

Executive producer and master showman Bobby Goldstein assured me this week that "Joey is doing very well," yet didn't wish to elaborate further as it's a "sensitive matter that I would not want to impede the show's continuation." Mr. Goldstein then explained he "thought long and hard about leaving the event in the episode ... [and] decided to do so in spite of the risks of alienating the 'violence watch dogs.' "

But is it all Barnum-ish bunk? Well, Mr. Grand who threatened just weeks ago to sue Goldstein over the "unlawful greed" that led to his controversial dismissal, and who has previously denied knowledge of scripted shenanigans during his tenure, now suggests fans reconsider Greco's seemingly grim fortune as "you'll question what's real and what's not" after reading the GQ article in which a Dallas stripper claims to have played a paid role in a lesbian love triangle.

Oh, what a tangled web we weave! Given the show's festering air of suspicion, conspiracy theorists willing to take a momentary break from the Zapruder footage might pose "stabbing" questions such as these:

Why not simply confront the cheater on dry land?
Might the guy falling in the lake be a diversion?
Where's the knife? None is ever seen.
If his face is blurred and his "identity withheld," why aren't repeated references to "Mitchell" and his mother's last name bleeped?
Suspect is never shown in police custody.
Greco arrives ashore less bloodied than moments before.
No one other than Joey applies pressure to his wound.
Why would anyone be allowed to leave the scene?
How does a maintenance supervisor afford a big-ass jet boat?
Why does Joey remain mic'd throughout his ordeal?
How are TWO cameras allowed along for the ambulance ride?
Despite shortness of breath, paramedics don't cut away clothing or even remove Joey's coat.
Why would an ambulance stop well short of the ER entrance?
Greco hosted all but the season's final episode?
How'd local media miss news of such a public assault?
Those puffs of smoke from the Grassy Knoll? Sorry, force of habit.

Also, the Dallas Observer ran an expose in October.