Don't get why he would join an English Nationalist Party.
Sounds as if he's got an eye on becoming an MSP in the 2026 election, and with the electoral system used for Scottish parliament and the likelihood of Reform getting a reasonable voteshare then being a pretty big fish (an ex tory council leader) in a small pond (reform potential candidates in Scotland) sounds like a pretty good route to success ... if you are ambition and unprincipled!!