Safe Habor 401k & Top Heavy Exemption

[B21]

This past month a client acquired a medical practice (Sub S corp) that has an existing safe harbor 401k plan. My client currently maintains a SEP under an LLC. The SEP is a prototype doc which allows acquired employees to be excluded pursuant to Sec 410(b)(6)©. For 2015, my client wants to contribute to both the SEP & 401k plans. The 401k plan receives only elective deferrals & a safe harbor match. Will my client's SEP contribution disqualify the 401k top heavy exemption under Sec 416(g)(4)(H)? Does Sec 410(b)(6)© extend the transition period to top heavy minimum requirements?