I see it as 'payback' for shitting on Max and RB performances this year. Remember the shittalking Mercedes/Toto/Lewis did at Monza? Yeah, those morons had it coming and I love it. This revelation will make some people uncomfortable at Mercedes. Some say it is normal practice (reaching out to other teams) and there is nothing special going on, and I would agree with that normally, if it weren't for the fact that Lewis claimed a while ago he did no such thing and focused 100% on Mercedes and getting the contract ironed out. Now Horner saw an opportunity to shit on the Mercedes team with this new information. Lewis did contact other teams (Ferrari for example, perhaps others as well?).
What will this accomplish you may ask? Nothing, absolutely nothing...other then making the next few meetings at Mercedes a bit uncomfortable :-)

And neither am I impressed by Lewis's driving for 2 years now. He will not become WC of course, he needs a better car for that, no shame or weird things here. But, if you look at Max when Mercedes dominated he was able to make races count, do incredible drives and the occasional win. No WC contender of course, just like Mercedes isn't atm, but he did win his race once or twice. 2 years without anything noticable, no exiting or special drive, no wins, anonymous. Even failed to get to Q3 on occasion. Yeah, color me unimpressed by Lewis and his driving.

And do not get me started on the revelation which we are witnessing on how bad Toto actually is as a Team Principal. Shockingly bad actually. His behavior, his lack of success and lack of direction on the team. He had years of success due to an insanely good engine and a driver who could utilize that situation. I applaud that actually, it is such a beast of an engine in those success years. Now that this advantage is gone, Toto is lost. Everything fails, for years, under his leadership. Again, color me unimpressed...