Dear brother,
May peace be with you.
As I’m sure you will appreciate, one's primary focus of interpreting any word in any given language is the ‘context’ it used in and how that word is understood by its native speakers in a similar context.
The verse clearly says "where the name of God is often mentioned". One would beg to ask the question, what would be the sense of mentioning 'God often' in trading places?
Clearly then, this is a reference to an oratory of some sort given the context of the verse.
Furthermore, the verb 'ba'a' (selling, trading) has a different meaning to the noun 'biya' (plural of bi'ah) as used in 22:40 to denote churches despite the same root.
With respect, this is a classic mistake made by some who may not have a proficiency or appreciation of the language they are attempting to interpret and attempt to apply meanings to words simply based on roots with limited appreciation of usage and contexts where meanings can possibly differ.
For example in English,
If I use the word 'hit' as a verb, what does it mean? e.g. "The cavalry hit at sunrise" - strike, blow?
If I use the word 'hit' as a noun, what does it mean? e.g. a Baseball hit?
There are then other uses of 'hit' depending on context. e.g. 'hit out' 'hit on' 'hit off', 'hit the high spots' etc.
Do the same words have the same meaning in different contexts? Does the same word as a verb and a noun necessarily have the same meaning? Of course not, as I'm sure you will agree.
Arabic is a spoken language just like any other.
I hope that helps, God willing.
Joseph.