It is not immediately obvious to me why who owns the instrumentation would be a driving factor in the time to see results. Both private research institutes and public institutes would want to get results out as quickly as possible, to capitalize on the PR effect. But that is moderated by the need to perform sufficienly accurate and detailed analysis, which takes time. Those pressures are the same for both public and private research institutes. If anything, the private institues would feel more pressure to publish results quickly, to improve their chances of obtaining future funding.
I cannot tell if you are comparing the quickness of this press release with the lack of results from the scientific packages on Phile, but I will address the (potential) comparison, just in case... Part of reason this press release (with the image of Philae bouncing) was out so quickly is that it does not require a very detailed and specific analysis (requiring roughly the equivalenth of image stictching in photoshop), and the results are fairly straightforward. Additionally, it is not really providing much in the way of new scientific information and so does not have as high a burden of proof. Additionally, the OSIRIS imager has been used to collect data for a while now, so presumably the OSIRIS team has a decent understanding of the real-world operation of the equipment, enabling them to quickly release images in which they were confident. In contrast, the Philae lander's instruments had not provided actual data before the landing, so the instrument teams still need to do the careful calibrations and analysis to understand the systematics.