India’s new buoy tender looks very different from those the USCG uses, looking more like an Offshore Support Vessel. Take a look at this report from Bairdmaritime. Maybe they are on to something.
The ship is 71.5 meters (235 feet) long.
Chuck Hill's CG Blog
Chuck Hill's CG Blog 
It makes you wonder why the USCG didn’t build Bouy tenders with a Helipad
Not sure how you would fit a flight deck on a buoy tender or why it is even necessary. Yes, all cutters are multi-mission, but a flight desk seems way overkill.
THV Galatea
THV Patricia
A flight deck if there is space available (and sufficient supporting structure) is a cheap addition. The biggest “problem” would be making sure there are sufficient crew trained as fireman. Of course there is a difference between a deck intended for use under way and one for use when at anchor. The question is why an organisation with so many helicopters and such a large territory to cover would not want its larger vessels to have aviation facilities?
Look at the Bouy tenders overseas. Some have Helipads on them.