Swamy,
Because Nammazhwar is “Krishna trishnA tattvam”

http://www.acharya.org/v/PrapannaParithranam/PrapannaParithranam07.html

Dasanudasan

Sri:

In fact, Nammazhwar’s indulgence in Krishna Avataram has earned him the title of ‘Krishna Trishna Tattvam’ (i.e. one who is peerless in his indulgence in Lord Krishna)

https://www.google.co.in/amp/s/sreevaishnavam.wordpress.com/2013/08/29/lord-krishna-in-the-eyes-of-azhwars-and-acharyas/amp/

Hare Krishna

Dasanudasan

A nammazhwar pasuram occurring (I like most)
“Naan Periya nee Periya enbadhai yaar arivar”

Velukkudi solliuvar,
“Naan Periya,” declared . “Nee Periya enbadhai yaar arivAr” adhan question?

Nee ulagatha vechundrukka
ulagatha vechundrukkara Unna naa en hrudhayathula (manasula) vechundrukken

Ippo yaar Yaara thaangaraa?

Dasanudasan

Sri Velukkudi Krishnan Swamy Thiruvadigaley Sharanam
????????????????

Srimathe Ramanujaya Namaha,

Sri Velukkudi Krishnan Swami ThiruvAdiyil adiyen DhandavAt Pranaamam,

Namaskaram,

Adiyen happen to come across “Thiruvaymozhi Saaram – Upanyasam by Sri Velukkudi Krishnan Swami” as below link, where Swami says about NammAzhwar’s Vaibhavam as:

• “Krishna Trishna Tatvam”  means Krishna Bhakthi. ‘Trishna’ means apaara Kaadhal/Anbu/Paitthyam (mad)/Moham on SriKrishna. “Kannan Allaal matrru oru Deivam Illai”, yendru namakku kaatti koduttha Mahacharyar Swami NammAzhwar.
• NammAzhwar is swayam ThiruKurunkudi Perumal Avataram.
•  Sriman NarayanAn took avatar in each Yugas based on Kulams as:

           1) Dattatreya (Brahmin Kulam in 1st Krita/Sathya Yugam)

           2) SriRama (Kshatriya Kulam in 2nd Treta Yugam)

           3) SriKrishna (Vaishya Kulam in 3rd Dvapara Yugam)

          4) NammAzhwar (Vellalar Non-Brahmin Kulam in 4th Kali Yugam)

• NammAzhvar is SriKrishna and SriKrishna is Swami NammAzhvar.

– More Vaibhavams of NammAzhwar in Swami’s upanyasam as below link.

https://www.youtube.com/watch?v=G8iFN-Fy8cE

Swami Velukkudi Krishnan Thiruvadigalaey Sharanam,

Acharyan Thiruvadigalaey Sharanam,

Adiyen Srinivasa (DhoddAcharya) Dasan,

Uyya Oraey Vazhi UdayavAr ThiruvAdi,

Sarvam SriKrishnarpanam Asthu