Former England captain Alastair Cook said Gill was right not to show his hand on Bumrah, with the fifth Test not beginning until Thursday.
"Even if he isn't going to play, you wouldn't tell people now, just on a purely tactical basis," Cook told Test Match Special.
"They made a mistake at the beginning of the series saying he could only play three, because you get thrown into a situation like now where the series is still on the line.
"If he's not fit to play, not playing is the right decision."
Gill did confirm that Bumrah's fellow seamer Akash Deep will be available at The Oval after missing the fourth Test with a groin injury.
But wicketkeeper Rishabh Pant will miss the final Test after suffering a broken foot in Manchester. Uncapped Tamil Nadu wicketkeeper Narayan Jagadeesan has been called up as cover.
Pant was struck on his right foot attempting a reverse-sweep at seam bowler Chris Woakes on the first day. He retired hurt on 37, then returned to bat again on day two, eventually moving to 54.
"Any amount of praise is not enough for him, batting with a broken foot," said India coach Gautam Gambhir. "Generations to come should talk about this, someone who batted with a broken foot.
"I hope he recovers and comes back quickly for us."
Gambhir also said he is "all for" the introduction of injury replacements in Test cricket. Currently, a replacement is only allowed if a player suffers a concussion.
India pulled off a remarkable escape to draw the fourth Test to keep the scoreline at 2-1 in England's favour.
Beginning their second innings 311 runs behind, the away side were reduced to 0-2 before lunch on day four.
But they batted through the next five sessions to leave Manchester with a draw. Gill, Ravindra Jadeja and Washington Sundar all made centuries to take India to 425-4, leading by 114 when a draw was agreed with 10 overs of the final day remaining.
"This is no less than a win for us," said Gill. "Having batted again around 300 runs off the lead, our batsmen put on a great display."