There's no such thing like we can build on rewards of good deeds of an ordered worship to leave this worship. Being inspired to do good deeds should in contrary be a reason to go ahead doing them. Also we don't know whether Allah has accepted our worship at all!
Read for example this sahih hadith:
Abu Huraira reported Allah's Messenger (ﷺ) as saying:
Do you know who is poor? They (the Companions of the Holy Prophet) said: A poor man amongst us is one who has neither dirham with him nor wealth. He (the Holy Prophet) said: The poor of my Umma would be he who would come on the Day of Resurrection with prayers and fasts and Zakat but (he would find himself bankrupt on that day as he would have exhausted his funds of virtues) since he hurled abuses upon others, brought calumny against others and unlawfully consumed the wealth of others and shed the blood of others and beat others, and his virtues would be credited to the account of one (who suffered at his hand). And if his good deeds fall short to clear the account, then his sins would be entered in (his account) and he would be thrown in the Hell-Fire.
(Sahih Muslim and Jami' at-Tirmdihi)
This hadith shows how easily one can loose gained rewards in a situation one will be in need of them!
You should also know that these rewards are only meant to encourage people to worship their and not elsewhere especially when in Mekka! Whether this amount would be counted for your prayer or not depends on many things, starting with your intention, your purity and how much effort you've done to pray as Allah wanted you to pray (praying correctly), so if any of us these days left the masjid al-Haram with >0 rewards he might be good! As again we have no idea whether Allah accepts our worship at all.
So if this person could provide any evidence for a prayer not being necessary for a person who prayed at the masjid al-Haram I guess all inhabitants of Mekka would have been happily sitting at home waiting for the day or resurrection! Else they should go ahead praying and performing good deeds!
You should also know that a person who rejects praying, while knowing that it is an order of Allah is considered an apostate and an apostate would never be able to enter Jannah! So what is the use of these rewards if he throw them away by rejecting to pray?
Last but not least, who are we beside or compared to a Prophet like 'Isa ibn Maryam () who said.
And He has made me blessed wherever I am and has enjoined upon me prayer and zakah as long as I remain alive. (19:31)
So we have to establish prayer as long as we are alive!
Also read my answers on related question like:
How do i know my Ramadan is accepted?
Will my zakat be accepted given that I am not performing prayer?
If someone do not pray 5 time, is he/she Kafer?