The impulse likely wasn’t any different, but the practical situation very much was.
St. Francis may not have spoken Arabic, but he appears to have had some way to communicate with the Sultan and his court. The article isn’t clear, but perhaps there was a translator present. Chau didn’t have that.
Though their cultures and religions were different, Francis and the Sultan had a basis for understanding each other’s roles and motivations. The Sultan knew what a Christian was and even had similar figures within his own tradition (the Sufis) to guide his treatment of Francis. The Sentinelese have no such context.
Further, while there was a chance that Francis could be killed on his risky mission, it wasn’t as though the Sultan was known for having anyone he didn’t recognize killed on sight. The Sentinelese do that.
Combining all these factors makes Chau’s effort far less likely to succeed than St. Francis’. Unlike the aforementioned Nate Saint, he didn’t even have peaceful contact that went wrong — as he could have predicted, he barely got to deliver word one before he was attacked. And given the linguistic and cultural barriers, there was no chance that first word (unlike Francis’ “Sultan!”) would have been enough to arouse curiosity and suggest what to do with the visitor.
On top of that, of course, his presence (and germs) endangered the islanders. I doubt St. Francis would ever have gone into the Sultan’s camp if he even suspected that his mere presence could kill everyone there.