As long as you don't need the 40 man roster spot for somebody else, its not hard to sneak him by. Stash him on the DL to open the year, send him to extended spring for a month or so, give him month on rehab at the appropriate level, activate him for a while to play defense and pinch run late in games, back to the DL, more rehab, a couple more weeks active, and repeat the process until you add him when rosters expand in September. Send him to winter ball to get the ABs he missed during the season and repeat the process next year. With a kid as young as Yorman, he'd be 22 and still have all his options after a couple of seasons accumulating his 90 days. Even if he'd need to go back to High A in 2015 (or more likely mid 2014 when his 90 days are up) with all his options, he could still be a pretty decent player by age 24 or 25. If I was the Astros, I'd absolutely take him unless some other team left somebody even better available. It's even easier for an AL team (the Astros next season) that has no need to PH for the pitcher or double switch. The 25th men are much less important in the AL and many times are defensive replacements and pinch runners anyway.
This can work with a kid this young. You wouldn't try it with a 25 year old in high A, but it would be a no brainer with a guy like Yorman IMO.