Some people on Twitter had previously expressed hopes that there could be constructive talks in the future. I assume she was referring to such conversations.The final bit "Hope for constructive engagement in future" sounds reasonable at first, but what does it really mean?
Unfortunately, some of the people who had expressed interest in talking with her are people who are still reporting being blocked (thus didn't even see the apology), despite not having said anything mean.
I realize "I apologise for any offense" is a bit weak, but at least the Lancet feels they needed to distance themselves from a "you [ME patients (in general?] are bullies" comment (note her specification that it was not from her journal--this sounds like an apology that her employer said she had to Tweet). This is a good sign, IMO.
We go from major British medical journal editors happy to smear the entire set of ME patients as being terrible, harassing, worthless people, to distancing themselves from a remark that appears to indicate such a sentiment. Definitely progress towards rationality and common sense.
Additionally, it's hard to compose a good message in 140 characters. Difficult to tell a lot from the wording of such a short message.