Really, there was no meaningful 'realistic offer' he could have made, simply because so much of the deal became tangled up in internal Tory politicking. At one point the not exactly natural bedfellows of the Trade Unions and the Confederation of British Industry issued a joint statement calling on May to get her **** sorted (I paraphrase). And I doubt either of them have been reassured by BoJo's performance so far.
The line of questioning one gets to see here appears to want to establish the good guy in this whole shambles, by making the other the bad one.
It's the sort of mindless partisanship one gets to see from many of our "cousins", in trying to establish that all fault lies with the "other side", that which one rejects.
This extremely childish approach precludes any relevant analysis of the situation and thus, seeing how it encourages conclusions not based on pertinent perusal, is precisely as irrelevant as this poster accuses others of being.
Both Corbyn and Johnson, let alone those constituting their parties, were and are slaves to their particular set of circumstances and the primary item of those was, is and will be their personal ambitions.
The country itself, "this couldn't be done because they wouldn't do this", "they wouldn't do this because dem others did whatever", has long since become of secondary or even tertiary importance where argument on what developed is concerned.
The far more relevant issue is the total disintegration of what once was a political class that functioned (however badly) and that disintegration spreads to the whole bunch. And all desires to make this guy or that guy (depending on one's myopic preferences) the less accountable, detract from the issue that really needs future address.
That the whole shebang is a reflection of the whole nation's division is no excuse for those proclaiming to be leading, on the contrary, the spectacle of "constructive ambiguity" that we see with both Corby and Johnson is set to enhance that particular shambles. When a country has no alternatives to unprincipled dishonesty leading it, matters can only deteriorate further before they improve.
With, on the principle of every country eventually getting the government it deserves, general pain for its people being the only catalyst that will work.
And hopefully towards a path that won't tear a leaf from the Weimar book.