Paragraph 4 says people with LTR visa receive tax exemption status by royal decree.
4. There are also certain types of visa that fall outside of the RD tax code. The LTR visa for example received its tax exempt status by royal decree hence visa holders will not to be assessed for Thai tax and they are specifically excluded from this explanation.
And paragraph 8 says that if you're spending more than 179 days per year in Thailand, you will always be considered to be a tax resident in Thailand regardless of the type of visa you have.
8. If you stay in Thailand for more than a cumulative 179 days, between 1 January and 31 December each year, you will be and always were considered to be Tax Resident in Thailand during that year, regardless of the type of visa you have. It doesn’t matter that you may be Tax Resident in your home country or elsewhere or that you pay tax in those countries, Thailand will still regard you as Tax Resident. Tax Residency and Immigration status (and the visa you hold) are different things. Tax residency is based solely on the number of days you spend in Thailand and where you are at midnight on each day.
They seem contradictory