Yes, it might make it easy for people at night to travel free with a sob story. But that's presumably always been a problem, especially as drivers are instructed not to get out of their cab - and control will want them to keep moving.
Thus when I've been on a bus where someone has got on and walked by, called back by the driver, when the kid didn't respond, we proceeded. The driver didn't appear to do anything (like radio control) and this was in the middle of the day!
I expect many people already get away without paying. I've seen people with Oyster cards that fail being waved through, although not always. But, if you don't want to pay, I'm sure sooner or later you'll get what you want. As in there'll be another bus along in a few minutes so try again.
Given the tiny numbers of revenue protection officers, I get the feeling TfL isn't too concerned. It's easy to pretend the problem isn't that big a deal, which was always the case when the bendy buses were in operation and people got used to being able to step on and not even have to face the driver. In fact, the front doors were probably the ones used the least.
Perhaps TfL would get more strict in the future, but at the very least they'll probably have a long period where they are especially lenient and will instruct drivers accordingly. TfL wants this to succeed to save money, so avoiding bad press will be worth the loss in income (that won't show up anyway, as it could just be fewer people deciding to travel).