"defensible against" is a correct and usable phrase in written English
It means able to withstand or protect against an attack or criticism. Example: The lawyer argued that her client's actions were defensible against the accusations of fraud, presenting evidence to support her claim.
It would also make Fitbit's platform a bit more defensible against "dumb trackers" that only provide analytics without actually helping users to get off the couch.
If a company doesn't have something that is proprietary that makes it defensible against potential competitors, then its success will lead to its downfall.
(Oh, and, in some sense, it makes a licensed webOS more defensible against patent attacks, because of all the major players that had an official hand in its development).
In 1891 the Qing government decided to make Qingdao (commonly spelled "Tsingtao") defensible against naval attack and began to improve the existing fortifications of the town.
With internal dissent increasing, they joined these new fortifications to existing walls to form a redoubt defensible against attacks from land or sea, which contained a large warehouse into which the extremists moved most of the city's corn supply.
During this period, Lords were required to defend their castles by means of mercenaries, rather than the vassals of the earlier feudal system, and Simpson suggested that the Lord of Doune designed his tower to be defensible against his own, potentially rebellious, garrison.
"There is no defensible argument against this legislation," said Representative Renee Ellmers (R-NC).
"The one thing I couldn't get my head around was how did our mobile CRM give us a defensible position against Salesforce?
Recent qualitative work suggests that doctors perceive exception reporting to be an important, defensible safeguard against inappropriate or over treatment of patients.
Some have voted with Republicans against defensible tax hikes.
Western Washington University emeritus philosophy professor Phillip Montague says in an essay titled "Defending Defensive Targeted Killings" that use of this tactic against combatants can be seen as defensible and justified acts against terrorism or those who assist terrorist organizations.
