sandhyA Vandanam is a Nitya Karma which has to be done as long as one is alive and fit. Even while some one is abroad, he has to do that sincerely. When a dvija lives abroad under certain inevitable circumstances, it is always preferable to perform the nitya karma to the extent possible rather than giving up the same totally, quoting the SAstras.
SandhyA Vandanam is nothing but chanting and celebrating the splendour and glory of the Supreme in different forms. The bhAva of the KartA is more important than the ritualistic aspects involved.
What is not possible through VarNASrama dharma in such difficult circumstances can be compensated through chanting the mahAmantra. Thus the deficiencies (lopas) of karmAnushthAna can be addressed through devotional surrender to the Supreme.
One should not condemn the changing yuga dharmas and those dvijas who follow those, as the dvijas are suited to the yuga concerned.
yuge yuge ca ye dharmAs tatra tatra ye dvijAh !
teshAm nindA na kartavYA yugarUpa hi te dvijAh !!
-------- parAsara
dhyAyan krute yajan yajnaih tretAyAm dvAparercayan !
yadApnoti tadApnoti kalau sankIrtya keSavam !!
---- VyAsa
YAvanna kIrtayet rAmam kalikalmasha sambhavam !
tAvattishthati dehesmin bhayam cAtra pravartate !!
---- Sivasarvasvam
SrutismrutipurANeshu rAma nAma samIritam !
tannAma kIrtanam bhUyas tApatrayavinASanam !!
---- cyavana smruti
sarvapApa prasaktopi dhyAyannimishamacyutam !
punastapasvI bhavati panktipAvana pAvanah !!
----- PaiThInasI
natAvatpApamedhena yannAma hatam hareh !
atireka bhayAdAhuh prAyascittAntaram vrithA !!
------ YogayAjnavalkya
prAyascittAnyaSeshANi tapah karmAtmakAni vai !
yAni teshAmaSeshANAm krishNAnus smaraNam param !!
punastapasvI bhavati panktipAvana pAvanah !!
----- PaiThInasI
natAvatpApamedhena yannAma hatam hareh !
atireka bhayAdAhuh prAyascittAntaram vrithA !!
------ YogayAjnavalkya
prAyascittAnyaSeshANi tapah karmAtmakAni vai !
yAni teshAmaSeshANAm krishNAnus smaraNam param !!
------ SrI vishNu purANa
kalau kalmasha chittAnAm pApadravyopa jIvinAm !
vidhikriyA vihInAnAm gatir govinda kIrtanam !!
In conclusion, vipras should endeavour to do karmas to the extent possible and offer the fruit to BhagavAn in the true spirit of karma yoga. They should also do nAma japam and surrender unconditionally to BhagavAn.
A vipra who does vihita kamAnushthAna should not find fault with others who do not do as each one is driven by his own prArabdha karma. He should not think that he is superior to some one who does not do kamAnushthAna nor to a dedicated Bhakta who is always immersed in the thought of the Supreme.
जय जय श्रीराधे