There are two questions here: would this certification open employment prospects to you better than other options? And is this certification going to provide you with knowledge that will help you work within a fitness area different than the one you are in. Personal training and group fitness are somewhat different. That is one reason that they have developed different certification tracks.
That you ask the first and not the second suggests that you feel you have a fair bit of background already and may just want a way to demonstrate this, or that you feel you have the knowledge but would like the opportunity to practice those skills in a hands on environment. For the first you would do best with a nationally recognized, NCCA accredited certification. For the second you might do as well seeing if you can get an internship after you do the certification (and some certifications offer those kind of training opportunities).
This certification does not appear to be NCCA accredited. Many places look for that, though, as harris suggests, you should check with the places where you wish to teach.
This certification is a one day program. The last time I did my CPR and First Aid recertification it took a day. One day seems short for a major certification training program, unless it is set up for people who have already read and mastered most of the material in advance.
They also seem to offer a yoga certification that takes one day, and they say one is ready to teach a yoga class after taking it. The standard in yoga is set by the yoga alliance and the basic level of training that will be authorized by the alliance is a MINIMUM of 200 hours. The upper tier is 500 hours. I cannot imagine having more than the most surface understanding of the discipline after 1 day.
I can understand wanting to do a certification at a conference…. do it all at once…. limit the huge costs of travel and time…. however, I think it makes more sense to do what I would call a second tier certification…. i.e. if one has group fitness, one could do a one day training program to add a particular style of group cardio or group strength. If one has a personal training certification one could do a one day program to add in a certificate for a special population. I find with even the best workshops there is a lot I forget. You need time to practice, to sleep and study, and make the material your own through practice and repetition.