I have not experience with running any popular twitter handles, but I can imagine that they block lots of people for various reasons, ranging from trivial to non-trivial. Honestly, if I were you, I'd simply let it go and not care if you can.
Also, from the information you have given, from a certain point of view, you might come off a bit needy: You send in 5-6 proposals per year and send direct messages and mails to multiple people when you don't receive answers and you care about whether some twitter account is blocking you or not.
I am not saying you are needy, I am just saying it could come off that way and that might have lead to either being blocked or communicated in non-tactful ways.
The existence of the blog itself makes me think the truth wouldn't be as clear as it is presented. Was every rejected talk proposal accompanied by emails and tweets asking for explanation? One can be polite and annoying at the same time.
(that being said, their email reply was still unprofessional)
Yes, I asked for explanation of rejected proposals in 2017 and 2018. And I received it (they even officially encouraged failed proposers to ask for an explanation).
Also, from the information you have given, from a certain point of view, you might come off a bit needy: You send in 5-6 proposals per year and send direct messages and mails to multiple people when you don't receive answers and you care about whether some twitter account is blocking you or not.
I am not saying you are needy, I am just saying it could come off that way and that might have lead to either being blocked or communicated in non-tactful ways.