Why does Shatner have to embrace his co-workers as "his new best friends"?
Film is different. You work long hours. There is a sort of trench-like war-bonding that tends to take place on a set. If it doesn't happen, it's kind of weird. And when you keep coming back to work with actors over decades, you'd think some sort of familial bond would develop. But there is a famous clip on Youtube where Shatner even forgets Walter Koenig's name! Even if there's no law that says you're supposed to love your coworkers, I think you're entitled to express how you feel about them.
Still, look at who Shatner had most of his scenes with. Those were the people he saw most often and those guys (Nimoy in particular) were who he bonded with the most. The lower level actors had a lot of their scenes together and had the common bond of being "under the title" as it were. Even on a film set, do you become buddies with EVERYONE? I've done work at my utility company after Hurrican Sandy swept through New York and was working 16 hour days for a month (no weekends off) in a substation woth a bunch of people. In that time, we became very close, but there were some people I just didn't connect with.
People connect with who they connect with. And sure, you're entitled to say what you feel about them, but after all this time, it's tiresome.