I am glad you blocked this person. As you say, having written nothing themselves, and with no profile information they have no right to criticise. It is funny how we dwell more on the bad comments than the positive ones. The fact that the piece was boosted should negate his comment completely.
I had a comment criticising a poem I wrote once ( but at least it was from another poet), the next day the poem was boosted and it has been my most successful piece of writing on Medium to date. I had so many positive comments as well, that negated the negative comment. I also know that person meant well, and it has actually inspired me to work even harder on my writing.

You are a good writer, so don’t dwell, and just keep writing.