Here are the regs on this:
Q-7: When is a distribution from a plan a required minimum distribution under section 401(a)(9)?
A-7: (a)General rule. Except as provided in paragraphs (b) and (c) of this Q&A, if a minimum distribution is required for a calendar year, the amounts distributed during that calendar year are treated as required minimum distributions under section 401(a)(9), to the extent that the total required minimum distribution under section 401(a)(9) for the calendar year has not been satisfied. Accordingly, these amounts are not eligible rollover distributions. For example, if an employee is required under section 401(a)(9) to receive a required minimum distribution for a calendar year of $5,000 and the employee receives a total of $7,200 in that year, the first $5,000 distributed will be treated as the required minimum distribution and will not be an eligible rollover distribution and the remaining $2,200 will be an eligible rollover distribution if it otherwise qualifies. If the total section 401(a)(9) required minimum distribution for a calendar year is not distributed in that calendar year (e.g., when the distribution for the calendar year in which the employee reaches age 70 1/2 is made on the following April 1), the amount that was required but not distributed is added to the amount required to be distributed for the next calendar year in determining the portion of any distribution in the next calendar year that is a required minimum distribution.
https://www.law.cornell.edu/cfr/text/26/1.402(c)-2
Note it is clear and say if an RMD is required for a calendar year the amounts distributed during that year are treated as having the first dollars be the RMDs.
Note is doesn't say amounts distributed after the person terminates and then an RMD is required. If at any time in a year an RMD ever becomes required for 2017- which your facts say "yes" to that idea- any distribution during that year has the RMD in it. It can literally become a retroactive RMD upon the person's termination.
So while it is true if you give this lady an in-service today there is no RMD in the amount paid. If she quits any time in 2017 then any payment in 2017 has an RMD in it. So if that RMD ended up in the IRA it doesn't belong there.
This idea you might give an in-service not knowing if the 70.5 year old person might terminated later is a known quirk but how I described it is clearly how the regs read.