Apologies if already covered, but is this such a big deal for pilots?
We're back talking about the frog in boiling water.
A two knot increase, in itself is probably not such a big deal. The problem is that they shouldn't have the 5 knots in the first place. Any operation to a tailwind is inherently less safe than operating into a head wind. Not dramatically perhaps, but reducing safety for a non operational reason is very poor management. As you increase the tailwind, it simply becomes less safe. Go arounds (with all the noise they bring) become more likely. Floating and long landings are more likely. In many cases you're only a couple of knots away from the aircraft's limit...so a slight gust and over the limit; go around. Approaches with a tailwind are flown with less power, which means slower engine response, and in itself might force the use of more flap (for the drag) just to help with power/speed stability. The difference between landing with a 7 knot headwind and their proposed 7 tail is in the order of 20% more energy to get rid of after touchdown.
I always knocked ATC back when they were pushing downwind landings. Interestingly, they don't 'force' it, because then the authorities would have to accept some level of responsibility when it eventually goes awry. Which, sooner or later, it will.