All that God has made, expresses himself. The creation of luminaries in the heavens expresses something about Light. And God is Light; and in him is no darkness at all.
The creation of vegetation, the creation of animal life, expresses something about life itself. And all life is of God and from God.
I would not understand and appreciate what 'the Lion of the tribe of Judah' means, were I not aware of what a lion is, in the natural creation. Nor could I appreciate the Lamb of God who taketh away the sin of the world, had I not walked through the field beside my home and walked among the flock.
But it would be very wrong for me to take a lamb home and worship it. Or to paint a picture of a lamb and put it above my fireplace and idolise the image as some kind of representation of Jesus. In that sense my attitude is as strict as WLC 109 and the article describes my own thinking. I abhor all representations and images and have none in my own home.
However, I think there is a very big difference between appreciating the way God has expressed himself in his own creation, and idolatrously worshipping the creature rather than the Creator.
Likewise the elements. When I partake of bread and wine, it is in response and obedience to the words of Jesus himself, This do in remembrance of me. But of Christ, himself, the apostle says :
Wherefore henceforth know we no man after the flesh: yea, though we have known Christ after the flesh, yet now henceforth know we him no more. II Corinthians 5:16 KJV.
To see only the flesh of Jesus Christ, to remember only his historic and natural manhood, is failing of the remembrance and is close to (if not actually) idolatry.
We remember He, Himself : The Son of God, come incarnate, risen and ascended. And we remember the significance of what he did in his humanity and with his humanity.
But we are given elements as an aid. We are granted a focus and an ordinance. Because we are still in the body. Because that is how our (present) humanity works.
Just as we are granted the visionary images in the Book of the Revelation, it is something we need. Spiritual things are conveyed to us in the vehicle of prophetic imagery. We need something in our mind as a vehicle to which to attach the spiritual concepts. So that we can think of them with a human brain.
We are informed of a vision of the Son of man, his eyes as a flame of fire. It is very wrong to depict that in any way. It is misguided to imagine that Jesus actually looks like that, physically. It is one flame, not two, and the concept is spiritual. The natural is for the brain to process, but the spiritual concept is for faith. Likewise the elements of bread and wine. They are visibly there, but they are there as an aid to faith, not as an aid to idolatrous worship.
I do not think anyone should be burdened or conflicted in conscience by the existence of the elements upon the table at the memorial. Nor with the act of physically participating. But we do, all and always, need to be careful of idolatry of every kind. Covetousness, itself, is a form of idolatry.
As the Apostle John tells us, in the last words of his first epistle :
Little children, keep yourselves from idols. Amen. I John 5:21 KJV.
It is a constant exercise. We are enjoined to so do. And we need to be careful.
I respect the sensitivity of someone troubled by the question. But I do hope that they should be troubled no longer.