If communion belongs to Passover, can believers only take it once a year?

You are pressing on the honest edge of the argument, and you should. If 'do this' belongs to Passover, the natural worry is that the piece has just handed you a new rule, once a year and not a day sooner, which feels as much like machinery as the weekly schedule it critiques. That is a fair thing to guard against.

And you are right that Scripture is full of people blessing bread and lifting cups outside any single feast. Gratitude to HaShem over a meal is a daily Hebrew reflex, not an annual one. The piece does not deny that.

You may also sense that the real question is not 'how few times may I' but 'what did the cup actually belong to.' That is the better question, and it is the one the essay answers.

Here is what to set down: turning the appointed time into a new prohibition. Read Sergio's own words on the one verse people reach for here. Sha'ul (Paul) writes, 'as often as you eat this bread and drink the cup, you proclaim the Lord's death' (1 Corinthians 11:26), and the piece is careful: that clause is about meaning, not frequency; it neither founds a weekly cadence nor forbids remembering Him at other moments. In the essay's own words, 'I am not telling you that you may never bless bread and cup outside Pesach.'

The correction is narrower and truer than a rule. The appointed remembrance Yeshua (Jesus) filled, the zikaron He spoke His name into, belongs to Passover, a mo'ed (appointed time) whose date HaShem fixed (Exodus 12:14; Leviticus 23), and He is 'our Passover lamb' (1 Corinthians 5:7). What the institution did was not add extra remembrances; it pried the meal off the day HaShem appointed and bolted it to a calendar of its own choosing, and most of us were never shown the appointed time at all.

Do not take it from me. Read 1 Corinthians 11:25-26 and notice Sha'ul is correcting an abuse, not setting a clock. Then read Exodus 12:14 and ask who set the time of the remembrance, HaShem or the institution.