I think you should understand that the main and only function of emergency fund is to be an immediate responsive fund in the case of unforseen circumstances, so we don't have to tamper with our portfolio for survival during such moments.
Buying dips isn't an emergency and it's wrong to use your emergency funds to buy dips, it boils down to improper planning and bad cashflow management to buy dips with emergency fund.

What if an emergency comes up at the time you've used your emergency fund to buy the dip? if you don't have enough floating cash to tackle it, then you'll have to tamper with your portfolio for survival which isn't a good practice. Then you'll have to make a bigger error tampering with your portfolio because you failed in simple accumulation ethics which is to reserve emergency funds for real emergencies only.