It all began when Jason Isaacs (Captain Lorca) gave a candid interview with Metro, where he said he doesn't want anyone from the original series to make a stunt cameo on Discovery.
"Kirk doesn't come along for 10 years and when we meet him, he's 26, so it would be a weird timeline if [Isaacs' character met Kirk]. Someone asked which cast members from the existing series would you like to guest star. I think people watch good drama shows and they completely suspend their disbelief, they feel like they're looking through the keyhole at another world, if you do it well enough.
"If you have stunt celebrity cameo casting, it completely pulls them out of it. They feel like they're watching a Saturday Night Live sketch. So I just hope people believe our stories, are engaged with them, and I'm happy to meet Will Shatner in real life in a restaurant."
Naturally, the U.K. tabloid grossly took his words grossly out of context with a salacious headline: "Jason Isaacs hopes William Shatner won't appear in Star Trek: Discovery."
Word (however misrepresented) travels fast, it seems. The 86-year-old Shatner, who played the original Captain Kirk, inexplicably blocked Isaacs on Twitter, which Isaacs—rather than letting things simmer down—kicked things up a notch on his account.
There's no way of knowing whether Shatner was genuinely offended by Isaacs's comments, but petty Twitter beef is petty Twitter beef.