Not clear to me that this is true. The expense was incurred, they just claim it over 5 years. It's not clear that the same employee is required to be there in subsequent years to claim the expense from year 1 in year 2.
It doesn't really matter how many devs you have in any given year.
What 174 does is make software a capital expense with no choice in how it gets depreciated over time. It's like having to expense the electricians wages during factory construction over 5 years.