Business meeting - visa type

Since I was few times in Thailand as an employee (with non-imm visa + workpermit) and as a tourist as well, my friend asked for my advice about what visa type he really needs for a casual business meetings in Thailand. I checked the latest immigration rules, I believe made in July 2024, but honestly Im a bit lost in this matter.

He does not own a business, he is a regular blue collar worker who was requested by his employer to meet some clients in Thailand from time to time.

Previously when I was applying for a job I got non-immigrant Visa + workpermit but I was literally hired by a company in Thailand. In his case he does not want to start a business nor being hired there, just a meeting once a month.

What I have read is that you can do some casual business activities on a tourist stamp on arrival but this seems a bit inconsistent between Thai Embassies in different countries (different explanations on their webpages).

So the questions is...does he need to apply for business visa or business visa + work permit or can use 60days stamp on arrival as a tourist? Getting invitation letter from Thai company is not an issue for him.

Basically he wants enter the Kingdom fully legally with all the proper paper work done but the current rules seems a bit unclear.

PS. He asked visa agency but they gave him some "outdated" answer I would say.

Appreciate your help in this matter.