The original article gave entrepreneurs four reasons not to protect their tweets. Its premise was that a business account is meant to be found and read beyond an existing circle. That still makes sense, but a protected account is not foolish: it serves a different purpose.
What changes when posts are protected?
X explains that public posts are visible to everyone, while protected posts are visible only to approved followers. New followers must request access. Protected posts are not publicly discoverable in the same way and cannot be shared through the ordinary repost button. A reply to someone who does not follow you may also be invisible to that person.
Those are real limits for a business or professional trying to reach new people. An explanation is harder to share, potential clients cannot as easily see your work and conversations with strangers are harder to begin. A public account makes these things easier without guaranteeing attention or customers.
Choose the purpose of the account
If you use X mainly with a small private group, protecting posts may fit. Approved followers can still take screenshots or repeat what they see. Share only what you want those people to know even behind a lock.
For business use, decide which subjects belong in public and which conversations should happen elsewhere. The setting is not a marketing trick, but a choice between open conversation and limited distribution.